Redfin (RDFN) 10-K 12 Feb 20 2019 FY Annual report Financial data

Cover

Cover - USD ($)	12 Months Ended
	Dec. 31, 2019	Jan. 31, 2020	Jun. 30, 2019
Cover page.
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	001-38160
Entity Registrant Name	Redfin Corporation
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	74-3064240
Entity Address, Address Line One	1099 Stewart Street
Entity Address, Address Line Two	Suite 600
Entity Address, City or Town	Seattle
Entity Address, State or Province	WA
Entity Address, Postal Zip Code	98101
City Area Code	(206)
Local Phone Number	576-8333
Title of 12(b) Security	Common Stock, $0.001 par value per share
Trading Symbol	RDFN
Security Exchange Name	NASDAQ
Entity Well Known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 1,547,297,147
Entity Common Stock, Shares Outstanding		93,123,373
Documents Incorporated by Reference	The portions of the registrant's proxy statement to be filed in connection with the registrant’s 2020 Annual Meeting of Stockholders that are responsive to the disclosure required by Part III of Form 10-K are incorporated by reference into Part III of this Form 10-K.
Entity Central Index Key	0001382821
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 234,679	$ 432,608
Restricted cash	12,769	6,446
Short-term investments	70,029	0
Accounts receivable, net	19,223	15,363
Inventory	74,590	22,694
Loans held for sale	21,985	4,913
Prepaid expenses	14,822	11,916
Other current assets	3,496	2,307
Total current assets	451,593	496,247
Property and equipment, net	39,577	25,187
Right-of-use assets, net	52,004
Long-term investments	30,978	0
Goodwill and intangibles, net	11,504	11,992
Other non-current assets	10,557	9,395
Total assets	596,213	542,821
Current liabilities
Accounts payable	2,122	2,516
Accrued liabilities	37,979	30,837
Other payables	7,884	6,544
Warehouse credit facilities	21,302	4,733
Secured revolving credit facility	4,444	0
Current lease liabilities	11,408
Current portion of deferred rent	43	1,588
Total current liabilities	85,182	46,218
Non-current lease liabilities	59,869
Deferred rent		11,079
Convertible senior notes, net	119,716	113,586
Total liabilities	264,767	170,883
Stockholders’ equity
Common stock—par value $0.001 per share; 500,000,000 shares authorized; 93,001,597 and 90,151,341 shares issued and outstanding, respectively	93	90
Additional paid-in capital	583,097	542,829
Accumulated other comprehensive income	42	0
Accumulated deficit	(251,786)	(170,981)
Total stockholders’ equity	331,446	371,938
Total liabilities and stockholders’ equity	$ 596,213	$ 542,821

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, authorized (in shares)	500,000,000	500,000,000
Common stock, issued (in shares)	93,001,597	90,151,341
Common stock, outstanding (in shares)	93,001,597	90,151,341

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue	$ 779,796	$ 486,920	$ 370,036
Cost of revenue	635,693	367,496	258,216
Gross profit	144,103	119,424	111,820
Operating expenses
Technology and development	69,765	53,797	42,532
Marketing	76,710	44,061	32,251
General and administrative	76,874	65,500	53,009
Total operating expenses	223,349	163,358	127,792
Loss from operations	(79,246)	(43,934)	(15,972)
Interest income	7,146	5,416	882
Interest expense	(8,928)	(3,681)	0
Other income, net	223	221	88
Net loss	(80,805)	(41,978)	(15,002)
Accretion of redeemable convertible preferred stock	0	0	(175,915)
Net loss attributable to common stock—basic	(80,805)	(41,978)	(190,917)
Net loss attributable to common stock—diluted	$ (80,805)	$ (41,978)	$ (190,917)
Net loss per share attributable to common stock—basic and diluted (in dollars per share)	$ (0.88)	$ (0.49)	$ (4.47)
Weighted average shares of common stock—basic and diluted (in shares)	91,583,533	85,669,039	42,722,114
Net loss	$ (80,805)	$ (41,978)	$ (190,917)
Other comprehensive income:
Foreign currency translation adjustments	33	0	0
Unrealized gain on available-for-sale securities	9	0	0
Total comprehensive loss	(80,763)	(41,978)	(190,917)
Service
Revenue	539,288	441,927	359,545
Cost of revenue	390,504	320,883	247,832
Product
Revenue	240,508	44,993	10,491
Cost of revenue	$ 245,189	$ 46,613	$ 10,384

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Activities
Net loss	$ (80,805)	$ (41,978)	$ (15,002)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation and amortization	9,230	8,465	7,176
Stock-based compensation	27,814	20,438	11,101
Amortization of debt discount and issuance costs	6,385	2,584	0
Non-cash lease expense	6,940
Other	(663)	0	0
Change in assets and liabilities:
Accounts receivable, net	(3,861)	(2,029)	(2,709)
Inventory	(51,896)	(19,312)	(3,382)
Prepaid expenses and other assets	(3,539)	(5,725)	4,450
Accounts payable	(394)	617	(252)
Accrued liabilities and other payables	7,459	4,509	5,115
Lease liabilities	(7,209)
Deferred rent	1	(1,249)	749
Origination of loans held for sale	(395,638)	(86,023)	(11,008)
Proceeds from sale of loans originated as held for sale	378,566	83,001	9,117
Net cash (used in) provided by operating activities	(107,610)	(36,702)	5,355
Investing activities
Purchases of property and equipment	(15,533)	(8,303)	(12,113)
Purchases of investments	(136,265)	(2,000)	(992)
Sales of investments	11,486	0	2,741
Maturities of investments	24,400	0	0
Net cash used in investing activities	(115,912)	(10,303)	(10,364)
Financing activities
Proceeds from the issuance of shares resulting from employee equity plans	16,107	23,407	3,003
Tax payments related to net share settlements on restricted stock units	(5,126)	(1,426)	0
Borrowings from warehouse credit facilities	388,586	83,842	10,746
Repayments of warehouse credit facilities	(372,017)	(81,125)	(8,730)
Borrowings from secured revolving credit facility	4,444	0	0
Other payables - deposits held in escrow	883	2,158	273
Proceeds from issuance of convertible notes, net of issuance costs	0	138,953	0
Proceeds from initial public offering, net of underwriting discounts	0	0	148,088
Payment of initial public offering costs	0	0	(3,558)
Proceeds from follow on offering	0	107,593	0
Cash paid for debt issuance costs	(922)	0	0
Principal payments under finance lease obligations	(72)
Net cash provided by financing activities	31,883	273,402	149,822
Effect of exchange rate changes on cash and cash equivalents	32	0	0
Net change in cash, cash equivalents, and restricted cash	(191,607)	226,397	144,813
Cash, cash equivalents, and restricted cash:
Beginning of period	439,055	212,658	67,845
End of period	247,448	439,055	212,658
Supplemental disclosure of non-cash investing and financial activities
Cash paid for interest	2,460	0	0
Conversion of redeemable convertible preferred stock to common stock	0	0	831,331
Accretion of redeemable convertible preferred stock	0	0	(175,915)
Stock-based compensation capitalized in property and equipment	(1,280)	(522)	(268)
Leasehold improvements paid directly by lessor	$ (6,230)	$ (1,980)	$ (822)

Consolidated Statements of Chan

Consolidated Statements of Changes in Redeemable Convertible Preferred Stock and Stockholders' Equity/(Deficit) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income
Redeemable convertible preferred stock beginning balance (in shares) at Dec. 31, 2016	55,422,002
Redeemable convertible preferred stock beginning balance at Dec. 31, 2016	$ 655,416
Increase (Decrease) in Temporary Equity [Roll Forward]
Accretion of redeemable convertible preferred stock	$ 175,915
Conversion of redeemable convertible preferred stock to common stock (in shares)	(55,422,002)
Conversion of redeemable convertible preferred stock to common stock	$ (831,331)
Redeemable convertible preferred stock ending balance (in shares) at Dec. 31, 2017	0
Redeemable convertible preferred stock ending balance at Dec. 31, 2017	$ 0
Balance, beginning of period (in shares) at Dec. 31, 2016		14,687,024
Balance, beginning of period at Dec. 31, 2016	(563,734)	$ 15	$ 0	$ (563,749)	$ 0
Increase (Decrease) in Stockholders' Equity
Issuance of common stock, net (in shares)		10,615,650
Issuance of common stock related to initial public offering, net	148,088	$ 10	148,078
Initial public offering costs	(3,708)		(3,708)
Issuance of common stock pursuant to exercise of stock options (in shares)		744,215
Issuance of common stock pursuant to exercise of stock options	3,001	$ 1	3,000
Stock-based compensation	11,369		11,369
Accretion of redeemable convertible preferred stock	(175,915)		(8,690)	(167,225)
Conversion of redeemable convertible preferred stock to common stock (in shares)		55,422,002
Conversion of redeemable convertible preferred stock to common stock	831,331	$ 55	213,781	617,495
Net loss	(15,002)			(15,002)
Balance, end of period (in shares) at Dec. 31, 2017		81,468,891
Balance, end of period at Dec. 31, 2017	$ 235,430	$ 81	364,352	(129,003)	0
Redeemable convertible preferred stock ending balance (in shares) at Dec. 31, 2018	0
Redeemable convertible preferred stock ending balance at Dec. 31, 2018	$ 0
Increase (Decrease) in Stockholders' Equity
Issuance of common stock pursuant to employee stock purchase plan (in shares)		425,228
Issuance of common stock pursuant to employee stock purchase plan	6,588	$ 1	6,587
Issuance of common stock, net (in shares)		4,836,336
Issuance of common stock related to initial public offering, net	107,593	$ 5	107,588
Issuance of common stock pursuant to exercise of stock options (in shares)		3,203,528
Issuance of common stock pursuant to exercise of stock options	16,820	$ 3	16,817
Issuance of common stock pursuant to settlement restricted stock units (in shares)		306,079
Issuance of common stock pursuant to settlement of restricted stock units	0
Common stock surrendered for employees' tax liability upon settlement of restricted stock units (in shares)		(88,721)
Common stock surrendered for employees' tax liability upon settlement of restricted stock units	(1,426)		(1,426)
Equity component of convertible senior notes, net	27,951		27,951
Stock-based compensation	20,960		20,960
Net loss	$ (41,978)			(41,978)
Balance, end of period (in shares) at Dec. 31, 2018	90,151,341	90,151,341
Balance, end of period at Dec. 31, 2018	$ 371,938	$ 90	542,829	(170,981)	0
Redeemable convertible preferred stock ending balance (in shares) at Dec. 31, 2019	0
Redeemable convertible preferred stock ending balance at Dec. 31, 2019	$ 0
Increase (Decrease) in Stockholders' Equity
Issuance of common stock pursuant to employee stock purchase plan (in shares)		490,717
Issuance of common stock pursuant to employee stock purchase plan	$ 6,732		6,732
Issuance of common stock pursuant to exercise of stock options (in shares)	1,666,162	1,666,162
Issuance of common stock pursuant to exercise of stock options	$ 9,570	$ 2	9,568
Issuance of common stock pursuant to settlement restricted stock units (in shares)		966,037
Issuance of common stock pursuant to settlement of restricted stock units	0	$ 1	(1)
Common stock surrendered for employees' tax liability upon settlement of restricted stock units (in shares)		(272,660)
Common stock surrendered for employees' tax liability upon settlement of restricted stock units	(5,126)		(5,126)
Stock-based compensation	29,095		29,095
Other comprehensive income (loss)	42				42
Net loss	$ (80,805)			(80,805)
Balance, end of period (in shares) at Dec. 31, 2019	93,001,597	93,001,597
Balance, end of period at Dec. 31, 2019	$ 331,446	$ 93	$ 583,097	$ (251,786)	$ 42

Description of Business and Sum

Description of Business and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Summary of Significant Accounting Policies	Description of Business and Summary of Significant Accounting Policies Description of Business —Redfin Corporation was incorporated in October 2002 and is headquartered in Seattle, Washington. We operate an online real estate marketplace and provide real estate services, including assisting individuals in the purchase or sale of their home. We also provides title and settlement services, originate and sell mortgages, and buy and sell homes. We have operations located in multiple states across the United States and certain provinces in Canada. Initial Public Offering —On August 2, 2017, we completed our IPO whereby 10,615,650 shares of common stock were sold at a price of $15.00 per share, which included 1,384,650 shares pursuant to the underwriters' option to purchase additional shares. We received net proceeds of $144,380 after deducting the underwriting discount and offering expenses directly attributable to the IPO. Upon the closing of the IPO, all shares of the outstanding redeemable convertible preferred stock automatically converted into 55,422,002 shares of common stock on a one -for-one basis. Basis of Presentation —The consolidated financial statements and accompanying notes have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”). Principles of Consolidation —The consolidated financial statements include the accounts of Redfin and its wholly owned subsidiaries, including those entities in which we have a variable interest and of which we are the primary beneficiary. Intercompany transactions and balances have been eliminated. Certain Significant Risks and Business Uncertainties — We are subject to the risks and challenges associated with companies at a similar stage of development. These include dependence on key individuals, successful development and marketing of our offerings, and competition with larger companies with greater financial, technical, and marketing resources. Further, to achieve substantially higher revenue in order to become profitable, we may require additional funds that may not be available or may not be on terms that are acceptable to us. We operate in the online real estate marketplace and, accordingly, can be affected by a variety of factors. For example, our management believes that any of the following factors could have a significant negative effect on our future financial position, results of operations, and cash flows: negative macroeconomic factors affecting the health of the U.S. residential real estate industry, negative factors disproportionately affecting markets where the we derive most of our revenue, intense competition in the U.S. residential real estate industry, our inability to maintain or improve our technology offerings, our failure to obtain and provide comprehensive and accurate real estate listings, errors or inaccuracies in the business data that we rely on to make decisions, and our inability to attract homebuyers and home sellers to our website and mobile application. Use of Estimates — The preparation of consolidated financial statements, in conformity with GAAP, requires our management to make estimates and assumptions that affect the reported amounts of assets and liabilities and results of operations during the respective periods. Our estimates include, but are not limited to, valuation of deferred income taxes, stock-based compensation, net realizable value of inventory, capitalization of website and software development costs, the incremental borrowing rate for the determination of the present value of lease payments, recoverability of intangible assets with finite lives, fair value of our mortgage loans held for sale, fair value of reporting units for purposes of evaluating goodwill for impairment, and the fair value of the convertible feature related to our convertible senior notes (see Note 14). The amounts ultimately realized from the affected assets or ultimately recognized as liabilities will depend on, among other factors, general business conditions and could differ materially in the near term from the carrying amounts reflected in the consolidated financial statements. Cash and Cash Equivalents —We consider all highly liquid investments originally purchased by us with original maturities of three months or less at the date of purchase to be cash equivalents and classified as available-for-sale. Our cash equivalents consist primarily of money market instruments. We maintain cash and cash equivalent balances with financial institutions that exceed federally-insured limits. Restricted Cash and Other Payables —Restricted cash primarily consists of cash held in escrow on behalf of real estate buyers using our title and settlement services. Since we do not have rights to the cash, a corresponding customer deposit liability in the same amount is recognized in the consolidated balance sheets in other payables. When a real estate services transaction closes, the restricted cash transfers from escrow and the corresponding deposit liability is reduced. In addition, we have other restricted cash that is specifically designated to repay borrowings under warehouse credit facilities and the secured revolving credit facility. Investments —We have two types of investments: (i) available-for-sale investments that are available to support our operational needs and which are reported on the balance sheet as short-term and long-term investments and (ii) long-term equity investments accounted for under the cost method, which are reported in other non-current assets. Available-for-sale Our short-term and long-term investments consist primarily of U.S. treasury securities, all of which are classified as available-for-sale. Available-for-sale debt securities are recorded at fair value, and unrealized holding gains and losses are recorded as a component of accumulated other comprehensive income. Available-for-sale securities with maturities of one year or less and those identified by management at the time of purchase to be used to fund operations within one year are classified as short-term. All other available-for-sale securities are classified as long-term. We evaluate our available-for-sale securities, both ones classified as cash equivalents and as investments, for other-than-temporary impairment on a quarterly basis. Unrealized losses are charged against net earnings when a decline in fair value is determined to be other than temporary. We review factors to determine whether a loss is other than temporary, such as the length and extent of the fair value decline, the financial condition and near-term prospects of the issuer, and whether we have the intent to sell or will more likely than not be required to sell before the securities' anticipated recovery, which may be at maturity. Realized gains and losses are accounted for using the specific identification method. Purchases and sales are recorded on a trade date basis. Cost Method Investments Our long-term equity investment consist of a purchased equity interest in a privately held company for approximately $2,000 . The investment is an equity security without a readily determinable fair value and is accounted for at cost minus any impairment, plus or minus changes resulting from observable price changes in orderly transactions for identical or similar investments of the same issuer. We perform a qualitative assessment to consider impairment indicators and evaluate whether the investment is impaired as of the end of each reporting period. Fair Value — We account for certain assets and liabilities at fair value. Fair value is defined as the exchange price that would be received for an asset or an exit price paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The current accounting guidance for fair value measurements defines a three-level valuation hierarchy for disclosures as follows: Level 1 —Unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 —Inputs other than quoted prices included within Level 1 that are observable, unadjusted quoted prices in markets that are not active, or other inputs that are observable such as quoted prices for similar assets or liabilities in active markets, or can be corroborated by observable market data. Level 3 —Unobservable inputs that are supported by little or no market activity and require us to develop our own assumptions. The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. Our financial instruments consist of Level 1, Level 2, and Level 3 assets and (liabilities). Concentration of Credit Risk —Financial instruments that potentially subject us to concentrations of credit risk are primarily cash and cash equivalents and investments. We generally place our cash and cash equivalents and investments with major financial institutions we deem to be of high-credit-quality in order to limit our credit exposure. We maintain our cash accounts with financial institutions where, at times, deposits exceed federal insurance limits. Inventory — Our inventory represents homes purchased with the intent of resale and are accounted for under the specific identification method. Direct home acquisition and improvement costs are capitalized and tracked directly with each specific home. Homes are stated in inventory at cost and are reviewed on a home by home basis. If a home's estimated market value is less than the inventory cost then the home is written down to net realizable value. We classify inventory into three categories: homes for sale, homes not available for sale, and homes under improvement. Homes for sale represent homes that are currently listed on the market for sale. Homes not available for sale are generally recently purchased homes that have been temporarily rented back by the prior owner and are not listed on the market for sale. The rental period is typically less than 30 days. Homes-under-improvement are homes that are in the process of being prepared to be listed for sale. Variable Interest Entities —In connection with establishing a secured revolving credit facility to support the financing of homes that it purchases, RedfinNow formed a special purpose entity called RedfinNow Borrower, which is a wholly owned subsidiary of Redfin Corporation. We have determined that RedfinNow Borrower is a variable interest entity ("VIE") and that we are the primary beneficiary of the variable interest in RedfinNow Borrower based on our power to direct the activities that most significantly impact the economic outcomes of the entity through our role in designing the entity and managing the homes purchased and sold by the entity. We have potentially significant variable interest in the entity based upon our equity interest held in the VIE. As we have concluded that we are the primary beneficiary, we have included the accounts of the VIE in our consolidated financial statements. The lenders of the secured revolving credit facility do not have recourse against the general credit of the primary beneficiary beyond the circumstances disclosed in Note 14. See Note 14 for a summary of the secured revolving credit facility, including outstanding borrowings associated with the VIE and related collateral. Loans Held for Sale —Redfin Mortgage, a wholly owned subsidiary of Redfin Corporation, began originating residential mortgage loans in March 2017. Such mortgage loans are intended to be sold in the secondary mortgage market within a short period of time following origination. Mortgage loans held for sale consist of single-family residential loans collateralized by the underlying home. Mortgage loans held for sale are recorded at fair value based on either sale commitments or current market quotes for mortgage loans with similar characteristics. Other Current Assets —Other current assets consist primarily of miscellaneous non-trade receivables and interest rate lock commitments from mortgage origination operations (see Derivative Instruments below). Derivative Instruments —Redfin Mortgage is party to IRLCs with customers resulting from mortgage origination operations. IRLCs for single family mortgage loans that Redfin Mortgage intends to sell are considered free-standing derivatives. All free-standing derivatives are required to be recorded on our consolidated balance sheets at fair value. Since Redfin Mortgage can terminate a loan commitment if the borrower does not comply with the terms of the contract, and some loan commitments may expire without being drawn upon, these commitments do not necessarily represent future cash requirements. Interest rate market risk, related to the residential mortgage loans held for sale and IRLCs, is offset using forward sales commitments. We manage this interest rate risk through the use of forward sales commitments on both a best effort whole loans basis and on a mandatory basis. Forward sales commitments entered in to on a mandatory basis are done through the use of commitments to sell mortgage-backed securities. We do not enter into or hold derivatives for trading or speculative purposes. Changes in the fair value of IRLCs and forward sales commitments are recognized as revenue, and the fair values are reflected in other current assets and accrued liabilities, as applicable. We estimate the fair value of an interest rate lock commitment based on current market quotes for mortgage loans with similar characteristics, net of origination costs and fees adjusting for the probability that the mortgage loan will not fund according to the terms of commitment (referred to as a pull-through factor). The fair value measurements of our forward sales commitments use prices quoted directly to us from our counterparties. Property and Equipment —Property and equipment is recorded at cost and depreciated using the straight-line method over the estimated useful lives. Depreciation and amortization is included in cost of revenue, technology and development, and general and administrative and is allocated based on estimated usage for each class of asset. Leasehold improvements are amortized over the shorter of the lease term or the estimated useful life of the related asset. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation are removed from the accounts, and any resulting gain or loss is reflected in the consolidated statements of operations. Repair and maintenance costs are expensed as incurred. Costs incurred in the preliminary stages of website and software development are expensed as incurred. Once an application has reached the development stage, direct internal and external costs relating to upgrades or enhancements that meet the capitalization criteria are capitalized in property and equipment and amortized on a straight-line basis over their estimated useful lives. Maintenance and enhancement costs (including those costs in the post-implementation stages) are typically expensed as incurred, unless such costs relate to substantial upgrades and enhancements to the websites (or software) that result in added functionality, in which case the costs are capitalized as well. Capitalized software development activities placed in service are amortized over the expected useful lives of those releases. We view capitalized software costs as either internal use, or market and product expansion. Currently, internal use and expansion useful lives are estimated at two to three years . Estimated useful lives of website and software development activities are reviewed annually or whenever events or changes in circumstances indicate that intangible assets may be impaired and adjusted as appropriate to reflect upcoming development activities that may include significant upgrades or enhancements to the existing functionality. Intangible Assets —Intangible assets are finite lived and mainly consist of trade names, developed technology, and customer relationships and are amortized over their estimated useful lives of ten years . The useful lives were determined by estimating future cash flows generated by the acquired intangible assets. Amortization expense is included in cost of revenue. Impairment of Long-Lived Assets —Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. Recoverability of assets to be held and used is measured first by a comparison of the carrying amount of an asset to future undiscounted net cash flows expected to be generated by the asset. If such asset were considered to be impaired, an impairment loss would be recognized when the carrying amount of the asset exceeds the fair value of the asset. To date, no such impairment has occurred. Goodwill —Goodwill represents the excess of the purchase price over the fair value of the net tangible assets and identifiable intangible assets acquired in a business combination. Goodwill is not amortized, but is subject to impairment testing. We assess the impairment of goodwill on an annual basis, during the fourth quarter, or whenever events or changes in circumstances indicate that goodwill may be impaired. We assess goodwill for possible impairment by performing a qualitative assessment to determine whether it is more likely than not that the fair value of the reporting unit is less than its carrying amount. If we qualitatively determine that it is not more likely than the fair value of the reporting unit is less than its carrying amount, then no additional impairment steps are necessary. We performed a qualitative assessment and determined that it was not more likely than not that the fair value of our reporting unit for which goodwill has been assigned was less than its carrying amount. In evaluating whether it was more likely than not that the fair value of our reporting unit was less than its carrying amount we considered macroeconomic conditions, industry and market considerations, cost factors, overall financial performance, other relevant entity-specific events, potential events affecting its reporting unit, and changes in the fair value of our common stock. The primary qualitative factors we have considered in our analysis are our overall financial performance and the fair value of the reporting unit for which goodwill was assigned, which was substantially in excess of its book value. The aggregate carrying value of goodwill was $9,186 at December 31, 2019 and 2018. There have been no accumulated impairments to goodwill. Other Non-current Assets —Other assets consists primarily of leased building security deposits and an equity investment accounted for under the cost method. Leases —The extent of our lease commitments consists of operating leases for physical office locations with terms ranging from one to 11 years and finance leases for vehicles with terms of four years . We have accounted for the portfolio of leases by disaggregation based on the nature and term of the lease. Generally, the leases require a fixed minimum rent with contractual minimum rent increases over the term of the lease. Leases with an initial term of twelve months or less are not recorded on the balance sheet, but rather lease expense from these leases is recognized on a straight-line basis over the term of the lease. When available, the rate implicit in the lease to discount lease payments to present value would be used; however, none of our significant leases as of December 31, 2019 provide a readily determinable implicit rate. Therefore, we must estimate our incremental borrowing rate for each portfolio of leases to discount the lease payments based on information available at lease commencement. We have evaluated the performance of existing leases in relation to our leasing strategy and have determined that most renewal options would not be reasonably certain to be exercised. The right of use asset and related lease liability are determined based on the lease component of the consideration in each lease contract. We have evaluated our lease portfolio for appropriate allocation of the consideration in the lease contracts between lease and nonlease components based on standalone prices and determined the allocation per the contracts to be appropriate. Foreign Currency Translation —Our international operations generally use their local currency as their functional currency. Assets and liabilities are translated at exchange rates in effect at the balance sheet date. Income and expense accounts are translated at the average monthly exchange rates during the year. Resulting translation adjustments are reported as a component of other comprehensive income and recorded in accumulated other comprehensive income on our consolidated balance sheets. Income Taxes —Income taxes are accounted for using an asset and liability approach that requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the consolidated financial statement and tax bases of assets and liabilities at the applicable enacted tax rates. We establish a valuation allowance for deferred tax assets if it is more likely than not that these items will expire before we are able to realize their benefits or if future deductibility is uncertain. We believe that it is currently more likely than not that our deferred tax assets will not be realized and as such, have recorded a full valuation allowance for these assets. We evaluate the likelihood of the ability to realize deferred tax assets in future periods on a quarterly basis, and, when appropriate evidence indicates, will release the valuation allowance accordingly. The determination to provide a valuation allowance is dependent upon the assessment of whether it is more likely than not that sufficient taxable income will be generated to utilize the deferred tax assets. Based on the weight of the available evidence, which includes our historical operating losses, lack of taxable income, and accumulated deficit, we have provided a full valuation allowance against the U.S. tax assets resulting from the tax losses and credits carried forward. Revenue Recognition — We generate revenue primarily from commissions and fees charged on each real estate services transaction closed by our lead agents or partner agents , and from the sale of homes . Our key revenue components are brokerage revenue, partner revenue, property revenue, and other revenue. We have utilized the practical expedient in ASC 606 and elected not to capitalize contract costs for contracts with customers with durations of less than one year. We do not have significant remaining performance obligations or contract balances. Revenue earned but not received is recorded as accrued revenue in accounts receivable on our consolidated balance sheets, net of an allowance for doubtful accounts. Accrued revenue consisting of commission revenue, is known and is clearing escrow, and therefore it is not estimated. Nature and Disaggregation of Revenue Real Estate Services Brokerage Revenue— Brokerage revenue includes our offer and listing services, where our lead agents represent home buyers and home sellers. We recognize commission-based brokerage revenue upon closing of a brokerage transaction, less the amount of any commission refunds, closing-cost reductions, or promotional offers that may result in a material right. The transaction price is calculated by taking the agreed upon commission rate and applying that to the home's selling price. Brokerage revenue primarily contains a single performance obligation that is satisfied upon the closing of a real estate services transaction, at which point the entire transaction price is earned. We are not entitled to any commission until the performance obligation is satisfied and are not owed any commission for unsuccessful transactions, even if services have been provided. We may offer promotional pricing which results in a material right to our customers and represents an additional performance obligation, in which the transaction price is allocated based on standalone selling prices. Our promotional pricing offers have not resulted in a material impact to timing of revenue recognition or contract liabilities with our customers for the periods presented. Partner Revenue— Partner revenue consists of fees paid to us from partner agents or under other referral agreements, less the amount of any payments we make to customers. We recognize these fees as revenue on the closing of a transaction . The transaction price is a fixed percentage of the partner agent's commission. The partner agent or other entity related to our referral agreements directly remits the referral fee revenue to us. We are not entitled to any referral fee revenue until the related referred real estate services transaction closes. Properties Properties Revenue— Properties revenue consists of revenue earned when we sell homes that were previously bought directly from homeowners . Properties revenue is recorded at closing on a gross basis, representing the sales price of the home. Our contracts with customers contain a single performance obligation that is satisfied upon a transaction closing. We do not offer warranties for sold homes, and there are no continuing performance obligations following the transaction close date. Other Other Revenue— Other services revenue includes fees earned from mortgage origination services, title settlement services, Walk Score data services, and advertising. Substantially all fees and revenue from other services are recognized when the service is provided. Mortgage banking services are not subject to the guidance in ASC 606 as the scope of the standard does not apply to revenue on contracts accounted for under Transfers and Servicing (Topic 860) but are included in other services revenue to reconcile total revenue presented on the consolidated statements of operations to the disaggregation of revenue table below. Intercompany Eliminations Intercompany Eliminations— Revenue earned from transactions between operating segments are eliminated in consolidating our financial statements. Intercompany transactions primarily consist of services performed from our real estate services segment for our properties segment. Accounts Receivable and Allowance for Doubtful Accounts — We establish an allowance for doubtful accounts after reviewing historical experience, age of accounts receivable balances and any other known conditions that may affect collectability. The majority of our transactions are processed through escrow and collectability is not a significant risk. Accounts receivable related to real estate services and properties transactions represents closed transactions for which the cash has not yet been received. Cost of Revenue — Cost of revenue consists primarily of personnel costs (including base pay, benefits, and stock-based compensation), transaction bonuses, home-touring and field expenses, listing expenses, home costs related to our properties segment, office and occupancy expenses, and depreciation and amortization related to fixed assets and acquired intangible assets. Home costs related to our properties segment include home purchase costs, capitalized improvements, selling expenses directly attributable to the transaction, and home maintenance expenses. Technology and Development —Technology and development expenses primarily include personnel costs (including base pay, benefits, and stock-based compensation), data licenses, software and equipment, and infrastructure such as for data centers and hosted services. The expenses also include amortization of capitalized internal-use software and website and mobile application development costs. We expense research and development costs as incurred and record them in technology and development expenses. Advertising and Advertising Production Costs —We expense advertising costs as they are incurred and production costs as of the first date the advertisement takes place. Advertising costs totaled $62,536 , $33,457 , and $21,902 in 2019, 2018, and 2017 respectively, and are included in marketing expenses. Advertising production costs totaled $2,029 , $1,644 , and $1,609 in 2019, 2018, and 2017, respectively, and are included in marketing expenses. Stock-based Compensation — We account for stock-based compensation by measuring and recognizing as compensation expense the fair value of all share-based payment awards made to employees, including stock options and restricted stock unit awards, and shares forecasted to be issued pursuant to our ESPP, in each case based on estimated grant date fair values. Stock-based compensation expense is recognized over the requisite service period on a straight-line basis. The Black-Scholes-Merton option-pricing model is used to determine the fair value for stock options and shares forecasted to be issued pursuant to our ESPP. For restricted stock unit awards and performance stock unit awards we use the market value of our common stock on the date of grant to determine the fair value of the award. In valuing stock options and shares forecasted to be issued pursuant to our ESPP, we make assumptions about expected life, stock price volatility, risk-free interest rates and expected dividends. Expected Life —The expected term was estimated using the simplified method allowed under guidance from the U.S. Securities and Exchange Commission as our historical share option exercise experience does not provide a reasonable basis upon which to estimate expected term. Volatility —The expected stock price volatility for our common stock was estimated by taking the average historical price volatility for industry peers based on daily price observations. Industry peers consist of several public companies in the real estate brokerage and technology industries. Risk-Free Rate —The risk-free interest rate is based on the yields of U.S. Treasury securities with maturities similar to the expected term of the options for each option group. Dividend Yield —We have never declared or paid any cash dividends and do not presently plan to pay cash dividends in the foreseeable future. Consequently, an expected dividend yield of zero was used. Forfeiture Rate —Beginning on January 1, 2017, we adopted Accounting Standard Update ("ASU") 2016-09 and elected to account for forfeitures as they occur. Recently Adopted Accounting Pronouncements — In January 2019, we adopted ASU 2016-02, Leases (Topic 842) , using the optional alternative transition method under ASU 2018-11, Leases (Topic 842) Targeted Improvements . The optional alternative transition method applies the new leases standard at the adoption date and recognizes a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. We evaluated our portfolio of leases upon adoption and determined a cumulative-effect adjustment to the opening balance of retained earnings was not needed, as the portfolio of leases contained only operating leases. We elected the package of practical expedients permitted under the transition guidance within the standard, allowing us to carry forward the historical lease classification, carry forward the conclusions on whether current or expired contracts contain leases, and carry forward the accounting for initial direct costs for existing leases. Additionally, we elected the practical expedient for use of hindsight to determine the lease term for existing leases whereby we evaluated the performance of existing leases in relation to our leasing strategy and determined that most renewal options would not be reasonably certain to be exercised. This resulted in the shortening of lease terms for the existing leases. Adoption of the standard resulted in the recording of right of use assets and corresponding lease liabilities of $33,953 and $49,395 , respectively, as of January 1, 2019, the difference of which is due to lease incentives. Further description of the impact of this pronouncement is included in Note 6. In January 2019, we adopted the guidance in the SEC's final rule under Release No. 33-10532, Disclosure Update and Simplification. In August 2018, the SEC issued the final rule amending certain disclosure requirements that were redundant, duplicative, overlapping, outdated, or superseded. In addition, the amend

Segment Reporting and Revenue

Segment Reporting and Revenue	12 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
Segment Reporting and Revenue	Segment Reporting and Revenue In operation of the business, our management, including our chief operating decision maker, who is also our Chief Executive Officer, evaluates the performance of our operating segments based on revenue and gross profit. We do not analyze discrete segment balance sheet information related to long-term assets, all of which are located in the United States. All other financial information is presented on a consolidated basis. We have five operating segments and two reportable segments, real estate services and properties. We generate revenue primarily from commissions and fees charged on real estate services transactions closed by our lead agents or partner agents, and from the sale of homes . Our key revenue components are brokerage revenue, partner revenue, properties revenue, and other revenue. Information on each of the reportable and other segments and reconciliation to consolidated net loss is as follows: Year Ended December 31, 2019 2018 2017 Real estate services Brokerage revenue $ 496,480 $ 406,293 $ 330,372 Partner revenue 27,060 25,875 21,198 Total real estate services revenue 523,540 432,168 351,570 Cost of revenue 373,150 309,069 237,832 Gross profit $ 150,390 $ 123,099 $ 113,738 Properties Revenue 240,507 44,993 10,491 Cost of revenue 245,189 46,613 10,384 Gross profit $ (4,682 ) $ (1,620 ) $ 107 Other Revenue 17,634 9,882 7,975 Cost of revenue 19,239 11,937 10,000 Gross profit $ (1,605 ) $ (2,055 ) $ (2,025 ) Intercompany eliminations Revenue (1,885 ) (123 ) — Cost of revenue (1,885 ) (123 ) — Gross profit $ — $ — $ — Consolidated Revenue 779,796 486,920 370,036 Cost of revenue 635,693 367,496 258,216 Gross profit $ 144,103 $ 119,424 $ 111,820 Operating expenses 223,349 163,358 127,792 Interest income 7,146 5,416 882 Interest expense (8,928 ) (3,681 ) — Other income, net 223 221 88 Net loss $ (80,805 ) $ (41,978 ) $ (15,002 ) Revenue earned but not received is recorded as accounts receivable on our consolidated balance sheets, net of an allowance for doubtful accounts. Accounts receivable consists primarily of commission revenue and proceeds from the sale of homes and are known, and therefore it is not estimated. The following table presents the detail of accounts receivable for the periods presented: Year Ended December 31, 2019 2018 Accounts receivable $ 19,388 $ 15,529 Less: Allowance for doubtful accounts (165 ) (166 ) Accounts receivable, net $ 19,223 $ 15,363 The following table presents the activity in the allowance for doubtful accounts for the periods presented: Year Ended December 31, 2019 2018 2017 Balance, beginning of period $ 166 $ 160 $ 150 Charges (15 ) 43 81 Write-offs 14 (37 ) (71 ) Balance, end of period $ 165 $ 166 $ 160

Financial Instruments

Financial Instruments	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Financial Instruments	Financial Instruments A summary of assets and (liabilities) as of December 31, 2019 and 2018 related to our financial instruments, measured at fair value on a recurring basis and as reflected in our consolidated balance sheets, is set forth below: Balance as of December 31, 2019 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Cash equivalents Money market funds $ 221,442 $ 221,442 $ — $ — Short-term investments U.S. treasury securities 70,029 70,029 — — Loans held for sale 21,985 — 21,985 — Prepaid expenses and other current assets Forward sales commitments 4 — 4 — Interest rate lock commitments 496 — — 496 Total prepaid expenses and other current assets 500 — 4 496 Long-term investments U.S. treasury securities 30,978 30,978 — — Total assets $ 344,934 $ 322,449 $ 21,989 $ 496 Liabilities Accrued liabilities Forward sales commitments $ 57 $ — $ 57 $ — Interest rate lock commitments 58 — — 58 Total liabilities $ 115 $ — $ 57 $ 58 Balance as of December 31, 2018 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Cash equivalents Money market funds $ 425,776 $ 425,776 $ — $ — Loans held for sale 4,913 — 4,913 — Prepaid expenses and other current assets Interest rate lock commitments 254 — — 254 Total prepaid expenses and other current assets 254 — — 254 Total assets $ 430,943 $ 425,776 $ 4,913 $ 254 Liabilities Accrued liabilities Forward sales commitments $ 141 $ — $ 141 $ — Total liabilities $ 141 $ — $ 141 $ — There was no significant activity within Level 3 financial instruments during the periods presented. See Note 14 for the carrying amount and estimated fair value of our convertible senior notes. Assets and liabilities recognized or disclosed at fair value on a nonrecurring basis include items such as property and equipment, goodwill and other intangible assets, cost method investments, and other assets. These assets are measured at fair value if determined to be impaired. We did not record any significant nonrecurring fair value measurements after initial recognition for the year ended December 31, 2019. The following table summarizes the cost or amortized cost, gross unrealized gains and losses, and estimated fair market value of our cash, money market funds, restricted cash and available-for-sale investments as of December 31, 2019 and 2018: December 31, 2019 Fair Value Hierarchy Cost or Amortized Cost Unrealized Gains Unrealized Losses Estimated Fair Value Short-term Investments Long-term Investments Cash N/A 13,237 — — 13,237 — — Money markets funds Level 1 221,442 — — 221,442 — — Restricted cash N/A 12,769 — — 12,769 — — U.S. treasury securities Level 1 100,998 31 (22 ) 101,007 70,029 30,978 Total 348,446 31 (22 ) 348,455 70,029 30,978 December 31, 2018 Fair Value Hierarchy Cost or Amortized Cost Unrealized Gains Unrealized Losses Estimated Fair Value Short-term Investments Long-term Investments Cash N/A 6,832 — — 6,832 — — Money markets funds Level 1 425,776 — — 425,776 — — Restricted cash N/A 6,446 — — 6,446 — — Total 439,054 — — 439,054 — — There were no other than temporary impairments during the periods presented.

Inventory

Inventory	12 Months Ended
	Dec. 31, 2019
Inventory Disclosure [Abstract]
Inventory	Inventory A summary of inventory as of December 31, 2019 and 2018 is as follows: December 31, 2019 2018 Homes for sale $ 36,982 $ 12,649 Homes not available for sale 3,163 2,328 Homes under improvement 34,445 7,717 Inventory $ 74,590 $ 22,694 Inventory costs include direct home acquisition costs and any capitalized improvements, net of lower of cost or net realizable value write-downs applied on a specific home basis. As of December 31, 2019 and December 31, 2018 , lower of cost or net realizable value write-downs were $143 and $190 , respectively. The following is the inventory activity for the year ended December 31, 2019: Inventory as of December 31, 2018 $ 22,694 Purchases and capitalized improvements to inventory 274,758 Relief of inventory to cost of revenue (222,909 ) Lower of cost or net realizable value write-downs, net 47 Inventory as of December 31, 2019 $ 74,590

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Property and Equipment	Property and Equipment A summary of property and equipment as of December 31, 2019 and 2018 is as follows: December 31, Useful Lives (years) 2019 2018 Leasehold improvements Shorter of lease term or economic life $ 28,141 $ 19,285 Website and software development costs 2-3 27,602 19,948 Computer and office equipment 3 4,846 2,956 Software 3 595 595 Furniture 7 6,965 3,933 Construction in progress 475 — Property and equipment, gross 68,624 46,717 Accumulated depreciation and amortization (29,047 ) (21,530 ) Property and equipment, net $ 39,577 $ 25,187 Depreciation and amortization expense for property and equipment amounted to $8,742 , $7,977 , and $6,688 for the years ended December 31, 2019 , 2018 , and 2017 , respectively. We capitalized software development costs, including stock-based compensation, of $8,396 , $5,796 , and $4,887 during the years ended December 31, 2019 , 2018 , and 2017 , respectively.

Leases

Leases	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Leases	Leases The components of lease activity were as follows: Lease Cost Classification Year Ended December 31, 2019 Operating lease cost: Operating lease cost (1) Cost of revenue $ 7,970 Operating lease cost (1) Operating expenses 3,648 Total operating lease cost $ 11,618 Finance lease cost: Amortization of right-of-use assets Cost of revenue $ 20 Interest on lease liabilities Cost of revenue 3 Total finance lease cost $ 23 (1) Includes lease expense with initial terms of twelve months or less of $2,180 for the year ended December 31, 2019. Maturity of Lease Liabilities Operating Leases Financing Leases 2020 $ 14,776 $ 60 2021 14,252 60 2022 13,506 60 2023 12,541 46 2024 10,947 — Thereafter 16,914 — Total lease payments $ 82,936 $ 226 Less: Interest and other (1) (11,865 ) (21 ) Present value of lease liabilities $ 71,071 $ 205 (1) Interest and other consists of interest expense related to capitalized right of use operating lease liabilities of $10,132 , interest expense related to capitalized right of use financing lease liabilities of $21 , commitments related to operating leases that have not yet commenced, and operating leases with initial terms of twelve months or less. Lease Term and Discount Rate December 31, 2019 Weighted average remaining operating lease term (years) 6.1 Weighted average remaining finance lease term (years) 3.8 Weighted average discount rate for operating leases 4.4 % Weighted average discount rate for finance leases 5.4 % Supplemental Cash Flow Information Year Ended Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 9,868 Operating cash flows from finance leases 3 Financing cash flows from finance leases 14 Right of use assets obtained in exchange for lease liabilities Operating leases $ 58,669 Finance leases 274
Leases	Leases The components of lease activity were as follows: Lease Cost Classification Year Ended December 31, 2019 Operating lease cost: Operating lease cost (1) Cost of revenue $ 7,970 Operating lease cost (1) Operating expenses 3,648 Total operating lease cost $ 11,618 Finance lease cost: Amortization of right-of-use assets Cost of revenue $ 20 Interest on lease liabilities Cost of revenue 3 Total finance lease cost $ 23 (1) Includes lease expense with initial terms of twelve months or less of $2,180 for the year ended December 31, 2019. Maturity of Lease Liabilities Operating Leases Financing Leases 2020 $ 14,776 $ 60 2021 14,252 60 2022 13,506 60 2023 12,541 46 2024 10,947 — Thereafter 16,914 — Total lease payments $ 82,936 $ 226 Less: Interest and other (1) (11,865 ) (21 ) Present value of lease liabilities $ 71,071 $ 205 (1) Interest and other consists of interest expense related to capitalized right of use operating lease liabilities of $10,132 , interest expense related to capitalized right of use financing lease liabilities of $21 , commitments related to operating leases that have not yet commenced, and operating leases with initial terms of twelve months or less. Lease Term and Discount Rate December 31, 2019 Weighted average remaining operating lease term (years) 6.1 Weighted average remaining finance lease term (years) 3.8 Weighted average discount rate for operating leases 4.4 % Weighted average discount rate for finance leases 5.4 % Supplemental Cash Flow Information Year Ended Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 9,868 Operating cash flows from finance leases 3 Financing cash flows from finance leases 14 Right of use assets obtained in exchange for lease liabilities Operating leases $ 58,669 Finance leases 274

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal Proceedings — On August 28, 2019, one of our former associate agents filed a complaint against us in the Superior Court of California, County of San Francisco alleging that we misclassified her as an independent contractor instead of an employee. Given the preliminary stage of this case and the claims and issues presented, we cannot estimate a range of reasonably possible losses. In addition to the matter discussed above, from time to time, we are involved in litigation, claims, and other proceedings arising in the ordinary course of our business. Except for the matter discussed above, we do not believe that any of the pending litigation, claims, and other proceedings are material to our business. Leases and Other Commitments —We lease office space under noncancelable operating leases with terms ranging from one to 11 years and vehicles under noncancelable finance leases with terms of four years . Generally, the operating leases require a fixed minimum rent with contractual minimum rent increases over the lease term. Other commitments relate to homes that are under contract to purchase through our properties business but that have not closed, and network infrastructure for our data operations. Future payments due under these agreements as of December 31, 2019 are as follows: Leases (1) Other Commitments 2020 $ 14,836 $ 26,048 2021 14,312 4,779 2022 13,566 5,148 2023 12,587 — 2024 and thereafter 27,861 — Total future minimum payments $ 83,162 $ 35,975 (1) The future minimum lease payments are presented on the same basis as the financial information presented in our consolidated financial statements and notes for the year ended December 31, 2018, as included in our Annual Report on Form 10-K for such period.

Acquired Intangible Assets

Acquired Intangible Assets	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Acquired Intangible Assets	Acquired Intangible Assets The following table presents details of our intangible assets subject to amortization as of December 31, 2019 and 2018. December 31, 2019 December 31, 2018 Useful Gross Accumulated Net Gross Accumulated Amortization Net Trade Names 10 $ 1,040 $ (546 ) $ 494 $ 1,040 $ (442 ) $ 598 Developed technology 10 2,980 (1,564 ) 1,416 2,980 (1,266 ) 1,714 Customer relationships 10 860 (452 ) 408 860 (366 ) 494 $ 4,880 $ (2,562 ) $ 2,318 $ 4,880 $ (2,074 ) $ 2,806 Amortization expense totaled $488 for each year ended December 31, 2019 , and 2018. We will recognize the remaining amortization expense of $2,318 over a five-year period, with the first four years recognizing expense of $488 per year, and the fifth year recognizing expense of $366 .

Accrued Liabilities

Accrued Liabilities	12 Months Ended
	Dec. 31, 2019
Payables and Accruals [Abstract]
Accrued Liabilities	Accrued Liabilities The following table presents the detail of accrued liabilities as of the dates presented: December 31, 2019 2018 Accrued compensation and benefits $ 30,462 $ 22,862 Miscellaneous accrued liabilities 7,517 7,975 Total accrued liabilities $ 37,979 $ 30,837

Other Payables

Other Payables	12 Months Ended
	Dec. 31, 2019
Payables and Accruals [Abstract]
Other Payables	Other Payables Other payables consists primarily of customer deposits for cash held in escrow on behalf of real estate buyers using our title and settlement services. Since we do not have rights to the cash, the customer deposits are recorded as a liability with a corresponding asset in the same amount recorded within restricted cash. The following table presents the detail of other payables as of the dates presented: December 31, 2019 2018 Customer deposits $ 7,109 $ 6,226 Miscellaneous payables 775 318 Total other payables $ 7,884 $ 6,544

Equity and Equity Compensation

Equity and Equity Compensation Plans	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Equity and Equity Compensation Plans	Equity and Equity Compensation Plans Common Stock —As of December 31, 2019 and 2018, our amended and restated certificate of incorporation authorized us to issue 500,000,000 shares of common stock with a par value of $0.001 per share. Preferred Stock — As of December 31, 2019 and 2018, our amended and restated certificate of incorporation authorized us to issue 10,000,000 shares of preferred stock at a par value of $0.001 , of which no shares were outstanding. Amended and Restated 2004 Equity Incentive Plan —We granted stock options under our 2004 Equity Incentive Plan, as amended ("2004 Plan"), until July 26, 2017, when we terminated it in connection with our IPO. Accordingly, no shares are available for future issuance under our 2004 Plan. Our 2004 Plan continues to govern outstanding equity awards granted thereunder. The term of each stock option under the plan is no more than 10 years , and each stock option generally vests over a four-year period. 2017 Equity Incentive Plan —Our 2017 Equity Incentive Plan ("2017 EIP") became effective on July 26, 2017 and provides for issuance of incentive and nonqualified common stock options and restricted stock units to employees, directors, officers, and consultants. The number of shares of common stock initially reserved for issuance under our 2017 EIP was 7,898,159 . The number of shares reserved for issuance under our 2017 EIP will increase automatically on January 1 of each calendar year beginning on January 1, 2018, and continuing through January 1, 2028, by the number of shares equal to the lesser of 5% of the total outstanding shares of our common stock as of the immediately preceding December 31 or an amount determined by our board of directors. The term of each stock option and restricted stock unit under the plan will not exceed 10 years, and each award generally vests over a four -year period. We have reserved shares of common stock for future issuance under our 2017 EIP as follows: December 31, 2019 2018 Stock options issued and outstanding 7,792,181 9,435,349 Restricted stock units outstanding 5,023,412 3,264,702 Shares available for future equity grants 7,100,499 5,068,013 Total shares reserved for future issuance 19,916,092 17,768,064 2017 Employee Stock Purchase Plan —Our ESPP was approved by the board of directors on July 27, 2017, and enables eligible employees to purchase shares of our common stock at a discount. Purchases will be accomplished through participation in discrete offering periods. We initially reserved 1,600,000 shares of common stock for issuance under our ESPP. The number of shares reserved for issuance under our ESPP will increase automatically on January 1 of each calendar year beginning after the first offering date and continuing through January 1, 2028, by the number of shares equal to the lesser of 1% of the total outstanding shares of our common stock as of the immediately preceding December 31 or an amount determined by our board of directors. On each purchase date, eligible employees will purchase our common stock at a price per share equal to 85% of the lesser of (i) the fair market value of our common stock on the first trading day of the offering period, and (ii) the fair market value of our common stock on the purchase date. We have reserved shares of common stock for future issuance under our ESPP as follows: Year Ended December 31, 2019 2018 Shares available for issuance at beginning of period 2,890,973 2,414,688 Shares issued during the period 490,717 425,228 Total shares available for future issuance at end of period 2,400,256 1,989,460 The weighted-average grant date fair value and the assumptions used in calculating fair values of shares forecasted to be issued pursuant to our ESPP are as follows: For the Offering Period beginning July 1, 2019 For the Offering Period beginning January 1, 2019 Expected life 0.5 years 0.5 years Volatility 39.60% 42.25% Risk-free interest rate 2.10% 2.51% Dividend yield —% —% Weighted-average grant date fair value $4.59 $3.80 Stock Options —The fair value of stock option awards was estimated at the grant date with the following weighted average assumptions: December 31, 2019 2018 2017 Expected life 6.5 years — 7 years Volatility 33.76% —% 37.88%-40.97% Risk-free interest rate 2.12% —% 1.96%-2.26% Dividend yield —% —% —% Weighted-average grant date fair value $3.22 — $4.86 The following table summarizes activity for stock options for the year ended December 31, 2019 : Weighted- Average Exercise Price Weighted Average Remaining Contractual Life (years) Outstanding as of January 1, 2019 9,435,349 $ 6.48 6.06 $ 74,669 Options granted 150,000 27.50 — — Options exercised (1,666,162 ) 5.74 Options forfeited (116,398 ) 9.16 Options canceled (10,608 ) 8.75 Outstanding as of December 31, 2019 7,792,181 $ 7.00 5.28 $ 111,122 Options exercisable as of December 31, 2019 7,043,042 $ 6.35 5.05 $ 104,141 The grant date fair value of stock options is recorded as stock-based compensation over the vesting period. As of December 31, 2019 , there was $3,573 of total unrecognized stock-based compensation related to stock options. These costs are expected to be recognized over a weighted-average period of 1.13 years . The total fair value of stock options vested during 2019, 2018, and 2017 was $4,747 , $7,089 , and $10,571 , respectively. The total intrinsic value of stock options exercised during 2019, 2018, and 2017 was $20,811 , $49,276 , and $9,322 , respectively. On June 1, 2019, we granted stock options subject to performance conditions, with a target of 150,000 shares and a maximum 300,000 shares, to our Chief Executive Officer. The options have an exercise price of $27.50 per share and have the same performance and vesting conditions as the restricted stock units subject to performance conditions that we granted in 2019 (the "2019 PSUs"). We granted no stock options in 2018. Restricted Stock Units —The following table summarizes activity for restricted stock units for the year ended December 31, 2019: Restricted Stock Units Weighted Average Grant-Date Fair Value Outstanding as of January 1, 2019 3,264,702 $ 19.68 Granted 3,184,465 18.19 Vested (966,037 ) 19.95 Forfeited or canceled (459,718 ) 19.65 Outstanding as of December 31, 2019 5,023,412 $ 18.69 The grant date fair value of restricted stock units is recorded as stock-based compensation over the vesting period. As of December 31, 2019, there was $86,549 of total unrecognized stock-based compensation related to restricted stock units, which is expected to be recognized over a weighted-average period of 3.06 years. As of December 31, 2019 , there were outstanding 314,999 restricted stock units subject to performance conditions ("PSUs") at 100% of the target level. Depending on our achievement of the performance conditions, the actual number of shares of common stock issuable upon vesting of PSUs will range from 0% to 200% of the target amount. For each PSU recipient, the award will vest, subject to the recipient continuing to provide service to us, upon our board of directors, or its compensation committee, certifying that we have achieved the PSU's related performance conditions. Stock-based compensation expense for PSUs will be recognized when it is probable that the performance conditions will be achieved. For the year ended December 31, 2019 , we recognized a net $284 of stock-based compensation expense for PSUs, which includes (i) an adjustment of ( $610 ) related to PSUs granted in 2018 as the probability of achieving the performance conditions was determined to be not probable and (ii) a charge of $894 related to the 2019 PSUs. Compensation Cost —The following table details, for each period indicated, (i) our stock-based compensation net of forfeitures, and the amount capitalized in internally developed software and (ii) includes changes to the probability of achieving outstanding performance-based equity awards, each as included in our consolidated statements of operations: Year Ended December 31, 2019 2018 2017 Cost of revenue $ 6,087 $ 5,567 $ 2,902 Technology and development 12,362 7,576 3,325 Marketing 1,418 662 487 General and administrative 7,947 6,633 4,387 Total stock-based compensation $ 27,814 $ 20,438 $ 11,101 We capitalize stock-based compensation related to work performed on internally developed software. There was $1,280 , $522 , and $268 of stock-based compensation that was capitalized in the years ended December 31, 2019, 2018, and 2017, respectively. All capitalized stock-based compensation is related to employees in technology and development.

Net Loss per Share Attributable

Net Loss per Share Attributable to Common Stock	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Net Loss per Share Attributable to Common Stock	Net Loss per Share Attributable to Common Stock Net loss per share attributable to common stock is computed by dividing the net loss attributable to common stock by the weighted-average number of common shares outstanding. We have outstanding stock options, restricted stock units, options to purchase shares under our ESPP, and convertible senior notes, which are considered in the calculation of diluted net income per share whenever doing so would be dilutive. As of December 31, 2019, we have one class of participating security, common stock, as all outstanding redeemable convertible preferred stock was converted to common stock on the date of our IPO, or August 2, 2017. Prior to August 2, 2017, we calculated basic and diluted net loss per share attributable to common stock in conformity with the two-class method required for companies with participating securities. Under the two-class method, net loss attributable to common stock was not allocated to the redeemable convertible preferred stock as the holders of redeemable convertible preferred stock did not have a contractual obligation to share in losses. The following table sets forth the calculation of basic and diluted net loss per share attributable to common stock during the periods presented: Year Ended December 31, 2019 2018 2017 Numerator: Net loss $ (80,805 ) $ (41,978 ) $ (15,002 ) Accretion of preferred stock — — (175,915 ) Net loss attributable to common stock—basic and diluted $ (80,805 ) $ (41,978 ) $ (190,917 ) Denominator: Weighted average shares —basic and diluted 91,583,533 85,669,039 42,722,114 Net loss per share attributable to common stock—basic and diluted $ (0.88 ) $ (0.49 ) $ (4.47 ) The following outstanding shares of common stock equivalents were excluded from the computation of the diluted net loss per share attributable to common stock for the periods presented because their effect would have been anti-dilutive. For the year ended December 31, 2017, shares of the redeemable convertible preferred stock were anti-dilutive. However, because the preferred stock converted into common stock on a one -for-one basis on August 2, 2017 upon the completion of our IPO, we included the preferred stock in the weighted average shares outstanding for the year ended December 31, 2017. Year Ended December 31, 2019 2018 2017 Stock options outstanding 7,792,181 9,435,349 13,180,950 Restricted stock units outstanding 5,023,412 3,264,702 981,276 Employee stock purchase plan — — — Total 12,815,593 12,700,051 14,162,226 We are required to consider the impact of our convertible senior notes on our diluted net income per share based on the treasury stock method as we have the ability, and intent, to settle any conversions of the notes solely in cash. The treasury stock method requires that the dilutive effect of common stock issuable upon conversion of the notes be computed in the periods in which we report net income. For the year ended December 31, 2019, there was no dilutive effect from the notes.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Our deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The following table represents the significant components of our deferred tax assets and liabilities for the periods presented: December 31, 2019 2018 Deferred tax assets Net operating loss carryforwards $ 49,211 $ 31,311 Credit carryforwards 8,638 6,655 Stock-based compensation 5,142 4,073 Compensation accruals 2,297 1,873 Lease liability 18,404 — Accruals and reserves 795 3,223 Gross deferred tax assets 84,487 47,135 Valuation allowance (62,274 ) (38,010 ) Total deferred tax assets, net of valuation allowance 22,213 9,125 Deferred tax liabilities Intangible assets (605 ) (734 ) Prepaid expenses (1,688 ) (1,503 ) Convertible senior notes (5,359 ) (6,888 ) Right-of-use assets (13,579 ) — Fixed assets (982 ) — Total deferred tax liabilities (22,213 ) (9,125 ) Net deferred tax assets and liabilities $ — $ — The valuation allowance increased by $24,264 during the year ended December 31, 2019 , increased by $8,192 during the year ended December 31, 2018 , and decreased by $8,489 during the year ended December 31, 2017 . The following table represents our net operating loss ("NOL") carryforwards as of December 31, 2019 and 2018 : December 31, 2019 2018 Federal $ 195,133 $ 125,850 Various states 10,421 6,180 Foreign 1,212 — Federal NOL carryforwards are available to offset federal taxable income and begin to expire in 2025, with NOL carryforwards of $109,484 generated after 2017 available to offset future U.S. federal taxable income over an indefinite period. State NOL carryforwards are available to offset future taxable income and begin to expire in 2019. NOL carryforward periods for the various states jurisdictions generally range from 5 to 20 years. Foreign NOL carryforward periods for foreign federal and provincial jurisdictions are generally 20 years. Additionally, net research and development credit carryforwards of $8,638 and $6,655 are available as of December 31, 2019 and 2018 , respectively, to reduce future tax liabilities. The research and development credit carryforwards begin to expire in 2026. Current tax laws impose substantial restrictions on the utilization of research and development credits and NOL carryforwards in the event of an ownership change, as defined by Internal Revenue Code Sections 382 and 383. Such an event may significantly limit our ability to utilize its net NOLs and research and development tax credit carryforwards. During 2017, we completed a Section 382 study. The study determined that we underwent an ownership change in 2006. Due to the Section 382 limitation determined on the date of the change in control in 2006, the NOL and research and development credit carryforwards have been reduced by $1,506 and $32 , respectively. The components of loss before benefit for income taxes for the years ended December 31, 2019 , 2018 , and 2017 were $(80,805) , $(41,978) , and $(15,002) , respectively. The following table is a reconciliation of the U.S. federal income tax at statutory rate to our effective income tax rate: December 31, 2019 2018 2017 U.S. federal income tax at statutory rate 21.00 % 21.00 % 34.00 % State taxes (net of federal benefit) 4.71 5.67 2.40 Stock-based compensation 1.20 7.51 (14.74 ) Permanent differences (0.97 ) (0.57 ) (0.29 ) Federal research and development credit 2.45 4.26 7.08 Change in valuation allowance (29.73 ) (37.33 ) (27.79 ) Other 1.34 (0.54 ) (0.66 ) Change in valuation allowance for Tax Act impact — — 84.37 Change in deferred balance before valuation allowance for Tax Reform impact — — (84.37 ) Effective income tax rate — % — % — % We did not record any tax benefits for the years ended December 31, 2019 , 2018 , and 2017 . The difference between the U.S. federal income tax at statutory rate of 21% for the years ended December 31, 2019 and 2018 , 34% for the year ended December 31, 2017 , and our effective tax rate in all periods is primarily due to a full valuation allowance related to our U.S. deferred tax assets and the change in corporate tax rate effective for tax years beginning after December 31, 2017 . We account for uncertainty in income taxes in accordance with ASC 740. We evaluate our tax positions in a two-step process, whereby we first determine whether it is more likely than not that a tax position will be sustained upon examination by the tax authority, including resolutions of any related appeals or litigation processes, based on technical merit. If a tax position meets the more-likely-than-not recognition threshold it is then measured to determine the amount of benefit to recognize in the financial statements. The tax position is measured as the largest amount of benefit that is greater than 50% likely of being realized upon ultimate settlement. The following table summarizes the activity related to unrecognized tax benefits: December 31, 2019 2018 Unrecognized benefit—beginning of year $ 1,663 $ 1,057 Gross decreases—prior year tax positions (127 ) — Gross increases—current year tax positions 623 606 Unrecognized benefit—end of year $ 2,159 $ 1,663 All of the unrecognized tax benefits as of December 31, 2019 and 2018 are accounted for as a reduction in our deferred tax assets. Due to our valuation allowance, no ne of the $2,159 and $1,663 of unrecognized tax benefits would affect our effective tax rate, if recognized. We do not believe it is reasonably possible that our unrecognized tax benefits will significantly change in the next twelve months. We recognize interest and penalties related to unrecognized tax benefits as income tax expense. There was no interest or penalties accrued related to unrecognized tax benefits for each year ended December 31, 2019 and 2018 and no liability for accrued interest or penalties related to unrecognized tax benefits as of December 31, 2019 . Our material income tax jurisdiction is the United States (federal). As a result of NOL carryforwards, we are subject to audit for all tax years for federal purposes. All tax years remain subject to examination in various other jurisdictions that are not material to our consolidated financial statements.

Debt

Debt	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Debt	Debt Warehouse Credit Facilities —To provide capital for the mortgage loans that it originates, Redfin Mortgage utilizes warehouse credit facilities that are classified as current liabilities in our consolidated balance sheets. Borrowings under each warehouse credit facility are secured by the related mortgage loan and rights and income related to the loans. The following table summarizes borrowings under these facilities as of the periods presented: Lender Borrowing Capacity as of December 31, 2019 Borrowings as of Borrowings as of December 31, 2018 Western Alliance Bank $ 24,500 $ 8,489 $ 1,141 Texas Capital Bank, N.A. 24,500 10,210 3,592 Flagstar Bank, FSB 15,000 2,603 N/A Total $ 64,000 $ 21,302 $ 4,733 Borrowings under the facility with Western Alliance Bank ("Western Alliance") mature on June 15, 2020 and generally bear interest at a rate equal to the greater of (i) one-month LIBOR plus 2.00% or (ii) 3.50% . The weighted average interest rate on outstanding borrowings as of December 31, 2019 and 2018 was 3.79% and 5.26% , respectively. The agreement governing the facility requires Redfin Mortgage to maintain certain financial covenants. Additionally, Redfin Corporation has agreed to make capital contributions in an amount necessary for Redfin Mortgage to satisfy its adjusted tangible net worth financial covenant under the agreement. Redfin Mortgage is in default of this facility because it failed to satisfy a financial covenant as of December 31, 2019, but Western Alliance has not enforced its remedy under the agreement of requiring Redfin Mortgage to repurchase all outstanding loans held by the lender. Borrowings under the facility with Texas Capital Bank, N.A. ("Texas Capital") mature on May 6, 2020 and generally bear interest at a rate equal to the greater of (i) the rate of interest accruing on the outstanding principal balance of the loan minus 0.5% or (ii) 3.5% . The weighted average interest rate on outstanding borrowings as of December 31, 2019 and 2018 was 3.51% and 4.11% , respectively. The agreement governing the facility requires Redfin Mortgage to maintain certain financial covenants. Additionally, Redfin Corporation has guaranteed Redfin Mortgage’s obligations under the agreement. Redfin Mortgage is in default of this facility because it failed to satisfy a financial covenant as of December 31, 2019, but Texas Capital has not enforced its remedies under the agreement, which principally include the rights to (i) cease purchasing participation interests in loans from Redfin Mortgage and (ii) sell all interests of Texas Capital or Redfin Mortgage in any loan subject to the agreement. Borrowings under the facility with Flagstar Bank, FSB ("Flagstar") generally bear interest at a rate equal to the greater of (i) one-month LIBOR plus 2.00% or (ii) 3.00% . The weighted average interest rate on outstanding borrowings as of December 31, 2019 was 3.69% .The Flagstar facility does not have a stated maturity date, but Flagstar may terminate the facility upon 30 days prior notice. Redfin Mortgage would be required to pay all amounts owed to Flagstar upon the facility's termination. Secured Revolving Credit Facility —To provide capital for the homes that it purchases, RedfinNow has, through a special purpose entity called RedfinNow Borrower, entered into a secured revolving credit facility with Goldman Sachs. Borrowings under the facility are secured by RedfinNow Borrower's assets, including the financed homes, as well as the equity interests in RedfinNow Borrower. The following table summarizes borrowings under this facility as of the period presented: Lender Borrowing Capacity as of December 31, 2019 Borrowings as of December 31, 2019 Goldman Sachs Bank USA $ 100,000 $ 4,444 The facility matures on January 26, 2021, but we may extend the maturity date for an additional six months to repay outstanding borrowings. Goldman Sachs may, at its sole option, finance a portion of RedfinNow Borrower's acquisition costs of qualified homes that have been purchased. The portion financed is based, in part, on how long the qualifying home has been owned by a Redfin entity. Borrowings under the facility generally bear interest at a rate of one-month LIBOR (subject to a floor of 0.50% ) plus 2.65% . The weighted average interest rate on outstanding borrowings as of December 31, 2019 was 4.45% . RedfinNow Borrower must repay all borrowings and accrued interest upon the termination of the facility, and it has the option to repay the borrowings, and the related interest, with respect to a specific financed home upon the sale of such home. In certain situations involving a financed home remaining unsold after a certain time period or becoming ineligible for financing under the facility, RedfinNow Borrower may be obligated to repay all or a portion of the borrowings, and related interest, with respect to such home prior to the sale of such home. In instances involving "bad acts," Redfin Corporation has guaranteed repayment of amounts owed under the facility, in some situations, and indemnification of certain expenses incurred, in other situations. As of December 31, 2019, RedfinNow Borrower had $16,200 of total assets, of which $7,456 related to inventory and $5,663 in cash and cash equivalents. For the year ended December 31, 2019, we amortized $256 of the debt issuance costs and recognized $17 of interest expense. Convertible Senior Notes — On July 23, 2018, we issued $143,750 aggregate principal amount of convertible senior notes. The notes are senior, unsecured obligations of Redfin Corporation and bear interest at a fixed rate of 1.75% per year, payable semi-annually in arrears on January 15 and July 15. The effective interest rate of the liability portion of the debt is 7.25% . The notes mature on July 15, 2023, unless earlier repurchased, redeemed or converted. As of December 31, 2019, no conversion events have occurred. We will settle conversions of the notes by paying or delivering, as the case may be, cash, shares of our common stock, or a combination of cash and shares of our common stock, at our election. We have the ability, and intend, to settle any conversions solely in cash. The convertible senior notes consisted of the following: Year Ended December 31, 2019 2018 Principal $ 143,750 $ 143,750 Less: debt discount, net of amortization (21,231 ) (26,636 ) Less: debt issuance costs, net of amortization (2,803 ) (3,528 ) Net carrying amount of the convertible senior notes $ 119,716 $ 113,586 The total estimated fair value of the notes as of December 31, 2019 and 2018 was approximately $142,672 and $117,875 , respectively, based on the closing trading price of the notes on last trading day for the period. The fair value has been classified as Level 2 within the fair value hierarchy given the limited trading activity of the notes. The following table sets forth total interest expense recognized related to the convertible senior notes for the periods presented: Year Ended December 31, 2019 2018 Amortization of debt discount $ 5,405 $ 2,280 Amortization of debt issuance costs 724 304 Total amortization of debt issuance costs and accretion of equity portion 6,129 2,584 Contractual interest expense 2,516 1,097 Total interest expense related to the convertible senior notes $ 8,645 $ 3,681

Description of Business and S_2

Description of Business and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation —The consolidated financial statements and accompanying notes have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”).
Principles of Consolidation	Principles of Consolidation —The consolidated financial statements include the accounts of Redfin and its wholly owned subsidiaries, including those entities in which we have a variable interest and of which we are the primary beneficiary. Intercompany transactions and balances have been eliminated.
Use of Estimates	Use of Estimates — The preparation of consolidated financial statements, in conformity with GAAP, requires our management to make estimates and assumptions that affect the reported amounts of assets and liabilities and results of operations during the respective periods. Our estimates include, but are not limited to, valuation of deferred income taxes, stock-based compensation, net realizable value of inventory, capitalization of website and software development costs, the incremental borrowing rate for the determination of the present value of lease payments, recoverability of intangible assets with finite lives, fair value of our mortgage loans held for sale, fair value of reporting units for purposes of evaluating goodwill for impairment, and the fair value of the convertible feature related to our convertible senior notes (see Note 14). The amounts ultimately realized from the affected assets or ultimately recognized as liabilities will depend on, among other factors, general business conditions and could differ materially in the near term from the carrying amounts reflected in the consolidated financial statements.
Cash and Cash Equivalents	Cash and Cash Equivalents —We consider all highly liquid investments originally purchased by us with original maturities of three months or less at the date of purchase to be cash equivalents and classified as available-for-sale. Our cash equivalents consist primarily of money market instruments. We maintain cash and cash equivalent balances with financial institutions that exceed federally-insured limits.
Restricted Cash and Other Payables	Restricted Cash and Other Payables —Restricted cash primarily consists of cash held in escrow on behalf of real estate buyers using our title and settlement services. Since we do not have rights to the cash, a corresponding customer deposit liability in the same amount is recognized in the consolidated balance sheets in other payables. When a real estate services transaction closes, the restricted cash transfers from escrow and the corresponding deposit liability is reduced. In addition, we have other restricted cash that is specifically designated to repay borrowings under warehouse credit facilities and the secured revolving credit facility.
Investments	Investments —We have two
Fair Value	Fair Value — We account for certain assets and liabilities at fair value. Fair value is defined as the exchange price that would be received for an asset or an exit price paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The current accounting guidance for fair value measurements defines a three-level valuation hierarchy for disclosures as follows: Level 1 —Unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 —Inputs other than quoted prices included within Level 1 that are observable, unadjusted quoted prices in markets that are not active, or other inputs that are observable such as quoted prices for similar assets or liabilities in active markets, or can be corroborated by observable market data. Level 3 —Unobservable inputs that are supported by little or no market activity and require us to develop our own assumptions. The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. Our financial instruments consist of Level 1, Level 2, and Level 3 assets and (liabilities).
Concentration of Credit Risk	Concentration of Credit Risk —Financial instruments that potentially subject us to concentrations of credit risk are primarily cash and cash equivalents and investments. We generally place our cash and cash equivalents and investments with major financial institutions we deem to be of high-credit-quality in order to limit our credit exposure. We maintain our cash accounts with financial institutions where, at times, deposits exceed federal insurance limits.
Inventory	Inventory — Our inventory represents homes purchased with the intent of resale and are accounted for under the specific identification method. Direct home acquisition and improvement costs are capitalized and tracked directly with each specific home. Homes are stated in inventory at cost and are reviewed on a home by home basis. If a home's estimated market value is less than the inventory cost then the home is written down to net realizable value. We classify inventory into three categories: homes for sale, homes not available for sale, and homes under improvement. Homes for sale represent homes that are currently listed on the market for sale. Homes not available for sale are generally recently purchased homes that have been temporarily rented back by the prior owner and are not listed on the market for sale. The rental period is typically less than 30 days. Homes-under-improvement are homes that are in the process of being prepared to be listed for sale.
Variable Interest Entities	Variable Interest Entities —In connection with establishing a secured revolving credit facility to support the financing of homes that it purchases, RedfinNow formed a special purpose entity called RedfinNow Borrower, which is a wholly owned subsidiary of Redfin Corporation. We have determined that RedfinNow Borrower is a variable interest entity ("VIE") and that we are the primary beneficiary of the variable interest in RedfinNow Borrower based on our power to direct the activities that most significantly impact the economic outcomes of the entity through our role in designing the entity and managing the homes purchased and sold by the entity. We have potentially significant variable interest in the entity based upon our equity interest held in the VIE. As we have concluded that we are the primary beneficiary, we have included the accounts of the VIE in our consolidated financial statements. The lenders of the secured revolving credit facility do not have recourse against the general credit of the primary beneficiary beyond the circumstances disclosed in Note 14. See Note 14 for a summary of the secured revolving credit facility, including outstanding borrowings associated with the VIE and related collateral.
Loans Held for Sale	Loans Held for Sale —Redfin Mortgage, a wholly owned subsidiary of Redfin Corporation, began originating residential mortgage loans in March 2017. Such mortgage loans are intended to be sold in the secondary mortgage market within a short period of time following origination. Mortgage loans held for sale consist of single-family residential loans collateralized by the underlying home. Mortgage loans held for sale are recorded at fair value based on either sale commitments or current market quotes for mortgage loans with similar characteristics.
Other Current Assets	Other Current Assets —Other current assets consist primarily of miscellaneous non-trade receivables and interest rate lock commitments from mortgage origination operations (see Derivative Instruments below).
Derivatives Instruments	Derivative Instruments —Redfin Mortgage is party to IRLCs with customers resulting from mortgage origination operations. IRLCs for single family mortgage loans that Redfin Mortgage intends to sell are considered free-standing derivatives. All free-standing derivatives are required to be recorded on our consolidated balance sheets at fair value. Since Redfin Mortgage can terminate a loan commitment if the borrower does not comply with the terms of the contract, and some loan commitments may expire without being drawn upon, these commitments do not necessarily represent future cash requirements. Interest rate market risk, related to the residential mortgage loans held for sale and IRLCs, is offset using forward sales commitments. We manage this interest rate risk through the use of forward sales commitments on both a best effort whole loans basis and on a mandatory basis. Forward sales commitments entered in to on a mandatory basis are done through the use of commitments to sell mortgage-backed securities. We do not enter into or hold derivatives for trading or speculative purposes. Changes in the fair value of IRLCs and forward sales commitments are recognized as revenue, and the fair values are reflected in other current assets and accrued liabilities, as applicable. We estimate the fair value of an interest rate lock commitment based on current market quotes for mortgage loans with similar characteristics, net of origination costs and fees adjusting for the probability that the mortgage loan will not fund according to the terms of commitment (referred to as a pull-through factor). The fair value measurements of our forward sales commitments use prices quoted directly to us from our counterparties.
Property and Equipment	Property and Equipment —Property and equipment is recorded at cost and depreciated using the straight-line method over the estimated useful lives. Depreciation and amortization is included in cost of revenue, technology and development, and general and administrative and is allocated based on estimated usage for each class of asset. Leasehold improvements are amortized over the shorter of the lease term or the estimated useful life of the related asset. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation are removed from the accounts, and any resulting gain or loss is reflected in the consolidated statements of operations. Repair and maintenance costs are expensed as incurred. Costs incurred in the preliminary stages of website and software development are expensed as incurred. Once an application has reached the development stage, direct internal and external costs relating to upgrades or enhancements that meet the capitalization criteria are capitalized in property and equipment and amortized on a straight-line basis over their estimated useful lives. Maintenance and enhancement costs (including those costs in the post-implementation stages) are typically expensed as incurred, unless such costs relate to substantial upgrades and enhancements to the websites (or software) that result in added functionality, in which case the costs are capitalized as well. Capitalized software development activities placed in service are amortized over the expected useful lives of those releases. We view capitalized software costs as either internal use, or market and product expansion. Currently, internal use and expansion useful lives are estimated at two to three years . Estimated useful lives of website and software development activities are reviewed annually or whenever events or changes in circumstances indicate that intangible assets may be impaired and adjusted as appropriate to reflect upcoming development activities that may include significant upgrades or enhancements to the existing functionality.
Intangible Assets	Intangible Assets —Intangible assets are finite lived and mainly consist of trade names, developed technology, and customer relationships and are amortized over their estimated useful lives of ten years . The useful lives were determined by estimating future cash flows generated by the acquired intangible assets. Amortization expense is included in cost of revenue.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets —Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. Recoverability of assets to be held and used is measured first by a comparison of the carrying amount of an asset to future undiscounted net cash flows expected to be generated by the asset. If such asset were considered to be impaired, an impairment loss would be recognized when the carrying amount of the asset exceeds the fair value of the asset. To date, no such impairment has occurred.
Goodwill	Goodwill —Goodwill represents the excess of the purchase price over the fair value of the net tangible assets and identifiable intangible assets acquired in a business combination. Goodwill is not amortized, but is subject to impairment testing. We assess the impairment of goodwill on an annual basis, during the fourth quarter, or whenever events or changes in circumstances indicate that goodwill may be impaired. We assess goodwill for possible impairment by performing a qualitative assessment to determine whether it is more likely than not that the fair value of the reporting unit is less than its carrying amount. If we qualitatively determine that it is not more likely than the fair value of the reporting unit is less than its carrying amount, then no additional impairment steps are necessary.
Other Non-current Assets	Other Non-current Assets —Other assets consists primarily of leased building security deposits and an equity investment accounted for under the cost method.
Leases	Leases —The extent of our lease commitments consists of operating leases for physical office locations with terms ranging from one to 11 years and finance leases for vehicles with terms of four years . We have accounted for the portfolio of leases by disaggregation based on the nature and term of the lease. Generally, the leases require a fixed minimum rent with contractual minimum rent increases over the term of the lease. Leases with an initial term of twelve months or less are not recorded on the balance sheet, but rather lease expense from these leases is recognized on a straight-line basis over the term of the lease. When available, the rate implicit in the lease to discount lease payments to present value would be used; however, none of our significant leases as of December 31, 2019 provide a readily determinable implicit rate. Therefore, we must estimate our incremental borrowing rate for each portfolio of leases to discount the lease payments based on information available at lease commencement. We have evaluated the performance of existing leases in relation to our leasing strategy and have determined that most renewal options would not be reasonably certain to be exercised. The right of use asset and related lease liability are determined based on the lease component of the consideration in each lease contract. We have evaluated our lease portfolio for appropriate allocation of the consideration in the lease contracts between lease and nonlease components based on standalone prices and determined the allocation per the contracts to be appropriate.
Foreign Currency Translation	Foreign Currency Translation —Our international operations generally use their local currency as their functional currency. Assets and liabilities are translated at exchange rates in effect at the balance sheet date. Income and expense accounts are translated at the average monthly exchange rates during the year. Resulting translation adjustments are reported as a component of other comprehensive income and recorded in accumulated other comprehensive income on our consolidated balance sheets.
Income Taxes	Income Taxes —Income taxes are accounted for using an asset and liability approach that requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the consolidated financial statement and tax bases of assets and liabilities at the applicable enacted tax rates. We establish a valuation allowance for deferred tax assets if it is more likely than not that these items will expire before we are able to realize their benefits or if future deductibility is uncertain. We believe that it is currently more likely than not that our deferred tax assets will not be realized and as such, have recorded a full valuation allowance for these assets. We evaluate the likelihood of the ability to realize deferred tax assets in future periods on a quarterly basis, and, when appropriate evidence indicates, will release the valuation allowance accordingly. The determination to provide a valuation allowance is dependent upon the assessment of whether it is more likely than not that sufficient taxable income will be generated to utilize the deferred tax assets. Based on the weight of the available evidence, which includes our historical operating losses, lack of taxable income, and accumulated deficit, we have provided a full valuation allowance against the U.S. tax assets resulting from the tax losses and credits carried forward.
Revenue Recognition	Revenue Recognition — We generate revenue primarily from commissions and fees charged on each real estate services transaction closed by our lead agents or partner agents , and from the sale of homes . Our key revenue components are brokerage revenue, partner revenue, property revenue, and other revenue. We have utilized the practical expedient in ASC 606 and elected not to capitalize contract costs for contracts with customers with durations of less than one year. We do not have significant remaining performance obligations or contract balances. Revenue earned but not received is recorded as accrued revenue in accounts receivable on our consolidated balance sheets, net of an allowance for doubtful accounts. Accrued revenue consisting of commission revenue, is known and is clearing escrow, and therefore it is not estimated. Nature and Disaggregation of Revenue Real Estate Services Brokerage Revenue— Brokerage revenue includes our offer and listing services, where our lead agents represent home buyers and home sellers. We recognize commission-based brokerage revenue upon closing of a brokerage transaction, less the amount of any commission refunds, closing-cost reductions, or promotional offers that may result in a material right. The transaction price is calculated by taking the agreed upon commission rate and applying that to the home's selling price. Brokerage revenue primarily contains a single performance obligation that is satisfied upon the closing of a real estate services transaction, at which point the entire transaction price is earned. We are not entitled to any commission until the performance obligation is satisfied and are not owed any commission for unsuccessful transactions, even if services have been provided. We may offer promotional pricing which results in a material right to our customers and represents an additional performance obligation, in which the transaction price is allocated based on standalone selling prices. Our promotional pricing offers have not resulted in a material impact to timing of revenue recognition or contract liabilities with our customers for the periods presented. Partner Revenue— Partner revenue consists of fees paid to us from partner agents or under other referral agreements, less the amount of any payments we make to customers. We recognize these fees as revenue on the closing of a transaction . The transaction price is a fixed percentage of the partner agent's commission. The partner agent or other entity related to our referral agreements directly remits the referral fee revenue to us. We are not entitled to any referral fee revenue until the related referred real estate services transaction closes. Properties Properties Revenue— Properties revenue consists of revenue earned when we sell homes that were previously bought directly from homeowners . Properties revenue is recorded at closing on a gross basis, representing the sales price of the home. Our contracts with customers contain a single performance obligation that is satisfied upon a transaction closing. We do not offer warranties for sold homes, and there are no continuing performance obligations following the transaction close date. Other Other Revenue— Other services revenue includes fees earned from mortgage origination services, title settlement services, Walk Score data services, and advertising. Substantially all fees and revenue from other services are recognized when the service is provided. Mortgage banking services are not subject to the guidance in ASC 606 as the scope of the standard does not apply to revenue on contracts accounted for under Transfers and Servicing (Topic 860) but are included in other services revenue to reconcile total revenue presented on the consolidated statements of operations to the disaggregation of revenue table below. Intercompany Eliminations Intercompany Eliminations— Revenue earned from transactions between operating segments are eliminated in consolidating our financial statements. Intercompany transactions primarily consist of services performed from our real estate services segment for our properties segment.
Accounts Receivable and Allowance for Doubtful Accounts	Accounts Receivable and Allowance for Doubtful Accounts — We establish an allowance for doubtful accounts after reviewing historical experience, age of accounts receivable balances and any other known conditions that may affect collectability. The majority of our transactions are processed through escrow and collectability is not a significant risk. Accounts receivable related to real estate services and properties transactions represents closed transactions for which the cash has not yet been received.
Cost of Revenue	Cost of Revenue — Cost of revenue consists primarily of personnel costs (including base pay, benefits, and stock-based compensation), transaction bonuses, home-touring and field expenses, listing expenses, home costs related to our properties segment, office and occupancy expenses, and depreciation and amortization related to fixed assets and acquired intangible assets. Home costs related to our properties segment include home purchase costs, capitalized improvements, selling expenses directly attributable to the transaction, and home maintenance expenses.
Technology and Development	Technology and Development —Technology and development expenses primarily include personnel costs (including base pay, benefits, and stock-based compensation), data licenses, software and equipment, and infrastructure such as for data centers and hosted services. The expenses also include amortization of capitalized internal-use software and website and mobile application development costs. We expense research and development costs as incurred and record them in technology and development expenses.
Advertising and Advertising Production Costs	Advertising and Advertising Production Costs —We expense advertising costs as they are incurred and production costs as of the first date the advertisement takes place. Advertising costs totaled $62,536 , $33,457 , and $21,902 in 2019, 2018, and 2017 respectively, and are included in marketing expenses. Advertising production costs totaled $2,029 , $1,644 , and $1,609 in 2019, 2018, and 2017, respectively, and are included in marketing expenses.
Stock-based Compensation	Stock-based Compensation — We account for stock-based compensation by measuring and recognizing as compensation expense the fair value of all share-based payment awards made to employees, including stock options and restricted stock unit awards, and shares forecasted to be issued pursuant to our ESPP, in each case based on estimated grant date fair values. Stock-based compensation expense is recognized over the requisite service period on a straight-line basis. The Black-Scholes-Merton option-pricing model is used to determine the fair value for stock options and shares forecasted to be issued pursuant to our ESPP. For restricted stock unit awards and performance stock unit awards we use the market value of our common stock on the date of grant to determine the fair value of the award. In valuing stock options and shares forecasted to be issued pursuant to our ESPP, we make assumptions about expected life, stock price volatility, risk-free interest rates and expected dividends. Expected Life —The expected term was estimated using the simplified method allowed under guidance from the U.S. Securities and Exchange Commission as our historical share option exercise experience does not provide a reasonable basis upon which to estimate expected term. Volatility —The expected stock price volatility for our common stock was estimated by taking the average historical price volatility for industry peers based on daily price observations. Industry peers consist of several public companies in the real estate brokerage and technology industries. Risk-Free Rate —The risk-free interest rate is based on the yields of U.S. Treasury securities with maturities similar to the expected term of the options for each option group. Dividend Yield —We have never declared or paid any cash dividends and do not presently plan to pay cash dividends in the foreseeable future. Consequently, an expected dividend yield of zero was used. Forfeiture Rate
Recently Adopted and Issued Accounting Pronouncements	Recently Adopted Accounting Pronouncements — In January 2019, we adopted ASU 2016-02, Leases (Topic 842) , using the optional alternative transition method under ASU 2018-11, Leases (Topic 842) Targeted Improvements . The optional alternative transition method applies the new leases standard at the adoption date and recognizes a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. We evaluated our portfolio of leases upon adoption and determined a cumulative-effect adjustment to the opening balance of retained earnings was not needed, as the portfolio of leases contained only operating leases. We elected the package of practical expedients permitted under the transition guidance within the standard, allowing us to carry forward the historical lease classification, carry forward the conclusions on whether current or expired contracts contain leases, and carry forward the accounting for initial direct costs for existing leases. Additionally, we elected the practical expedient for use of hindsight to determine the lease term for existing leases whereby we evaluated the performance of existing leases in relation to our leasing strategy and determined that most renewal options would not be reasonably certain to be exercised. This resulted in the shortening of lease terms for the existing leases. Adoption of the standard resulted in the recording of right of use assets and corresponding lease liabilities of $33,953 and $49,395 , respectively, as of January 1, 2019, the difference of which is due to lease incentives. Further description of the impact of this pronouncement is included in Note 6. In January 2019, we adopted the guidance in the SEC's final rule under Release No. 33-10532, Disclosure Update and Simplification. In August 2018, the SEC issued the final rule amending certain disclosure requirements that were redundant, duplicative, overlapping, outdated, or superseded. In addition, the amendments expanded the disclosure requirements on the analysis of stockholders' equity for interim financial statements. Under the amendments, an analysis of changes in each caption of stockholders' equity presented in the balance sheet must be provided in a note or separate statement. The analysis should present a reconciliation of the beginning balance to the ending balance of each period for which a statement of comprehensive income is required to be filed. In August 2018, the Financial Accounting Standards Board (the "FASB") issued authoritative guidance under ASU 2018-15, Intangibles—Goodwill and Other—Internal-Use Software: Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract . The ASU requires implementation costs incurred by customers in cloud computing arrangements (i.e., hosting arrangements) to be capitalized under the same premises of authoritative guidance for internal-use software, and deferred over the noncancelable term of the cloud computing arrangements plus any option renewal periods that are reasonably certain to be exercised by the customer or for which the exercise is controlled by the service provider. The ASU is effective for public entities for fiscal years beginning after December 15, 2019 and early adoption is permitted. We elected to early adopt this standard in the third quarter of 2019 on a prospective basis, which did not result in a material effect on our consolidated financial statements. In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820) , which modifies the disclosures on fair value measurements by removing the requirement to disclose the amount and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy and the policy for timing of such transfers. The ASU expands the disclosure requirements for Level 3 fair value measurements, primarily focused on changes in unrealized gains and losses included in other comprehensive income. The ASU is effective for public entities for fiscal years beginning after December 15, 2019, with early adoption permitted. We have elected to early adopt this ASU and determined the adoption did not result in a material impact to the disclosures included in Note 3. Recently Issued Accounting Pronouncements —I n June 2016, the FASB issued authoritative guidance under ASU 2016-13, Financial Instruments—Credit Losses (Topic 326), which modifies the measurement of credit losses on financial instruments. This guidance requires the use of an expected loss impairment model for instruments measured at amortized cost based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectibility of the reported amount. For available-for-sale debt securities, an entity is required to recognize credit losses through an allowance for credit losses rather than as an impairment. The ASU is effective for interim and annual reporting periods beginning after December 15, 2019, and early adoption is permitted. The adoption of this guidance requires a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. We have completed an assessment of the impact of the new standard on our consolidated financial statements and do not expect a material impact.

Segment Reporting and Revenue

Segment Reporting and Revenue - (Tables)	12 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
Reconciliation of Operating Profit (Loss) from Segments to Consolidated	Information on each of the reportable and other segments and reconciliation to consolidated net loss is as follows: Year Ended December 31, 2019 2018 2017 Real estate services Brokerage revenue $ 496,480 $ 406,293 $ 330,372 Partner revenue 27,060 25,875 21,198 Total real estate services revenue 523,540 432,168 351,570 Cost of revenue 373,150 309,069 237,832 Gross profit $ 150,390 $ 123,099 $ 113,738 Properties Revenue 240,507 44,993 10,491 Cost of revenue 245,189 46,613 10,384 Gross profit $ (4,682 ) $ (1,620 ) $ 107 Other Revenue 17,634 9,882 7,975 Cost of revenue 19,239 11,937 10,000 Gross profit $ (1,605 ) $ (2,055 ) $ (2,025 ) Intercompany eliminations Revenue (1,885 ) (123 ) — Cost of revenue (1,885 ) (123 ) — Gross profit $ — $ — $ — Consolidated Revenue 779,796 486,920 370,036 Cost of revenue 635,693 367,496 258,216 Gross profit $ 144,103 $ 119,424 $ 111,820 Operating expenses 223,349 163,358 127,792 Interest income 7,146 5,416 882 Interest expense (8,928 ) (3,681 ) — Other income, net 223 221 88 Net loss $ (80,805 ) $ (41,978 ) $ (15,002 )
Contract with Customer, Asset and Liability	The following table presents the detail of accounts receivable for the periods presented: Year Ended December 31, 2019 2018 Accounts receivable $ 19,388 $ 15,529 Less: Allowance for doubtful accounts (165 ) (166 ) Accounts receivable, net $ 19,223 $ 15,363 The following table presents the activity in the allowance for doubtful accounts for the periods presented: Year Ended December 31, 2019 2018 2017 Balance, beginning of period $ 166 $ 160 $ 150 Charges (15 ) 43 81 Write-offs 14 (37 ) (71 ) Balance, end of period $ 165 $ 166 $ 160

Financial Instruments (Tables)

Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Schedule of Assets, Liabilities, and Equity Measured at Fair Value on a Recurring Basis	A summary of assets and (liabilities) as of December 31, 2019 and 2018 related to our financial instruments, measured at fair value on a recurring basis and as reflected in our consolidated balance sheets, is set forth below: Balance as of December 31, 2019 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Cash equivalents Money market funds $ 221,442 $ 221,442 $ — $ — Short-term investments U.S. treasury securities 70,029 70,029 — — Loans held for sale 21,985 — 21,985 — Prepaid expenses and other current assets Forward sales commitments 4 — 4 — Interest rate lock commitments 496 — — 496 Total prepaid expenses and other current assets 500 — 4 496 Long-term investments U.S. treasury securities 30,978 30,978 — — Total assets $ 344,934 $ 322,449 $ 21,989 $ 496 Liabilities Accrued liabilities Forward sales commitments $ 57 $ — $ 57 $ — Interest rate lock commitments 58 — — 58 Total liabilities $ 115 $ — $ 57 $ 58 Balance as of December 31, 2018 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Cash equivalents Money market funds $ 425,776 $ 425,776 $ — $ — Loans held for sale 4,913 — 4,913 — Prepaid expenses and other current assets Interest rate lock commitments 254 — — 254 Total prepaid expenses and other current assets 254 — — 254 Total assets $ 430,943 $ 425,776 $ 4,913 $ 254 Liabilities Accrued liabilities Forward sales commitments $ 141 $ — $ 141 $ — Total liabilities $ 141 $ — $ 141 $ —
Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure	The following table summarizes the cost or amortized cost, gross unrealized gains and losses, and estimated fair market value of our cash, money market funds, restricted cash and available-for-sale investments as of December 31, 2019 and 2018: December 31, 2019 Fair Value Hierarchy Cost or Amortized Cost Unrealized Gains Unrealized Losses Estimated Fair Value Short-term Investments Long-term Investments Cash N/A 13,237 — — 13,237 — — Money markets funds Level 1 221,442 — — 221,442 — — Restricted cash N/A 12,769 — — 12,769 — — U.S. treasury securities Level 1 100,998 31 (22 ) 101,007 70,029 30,978 Total 348,446 31 (22 ) 348,455 70,029 30,978 December 31, 2018 Fair Value Hierarchy Cost or Amortized Cost Unrealized Gains Unrealized Losses Estimated Fair Value Short-term Investments Long-term Investments Cash N/A 6,832 — — 6,832 — — Money markets funds Level 1 425,776 — — 425,776 — — Restricted cash N/A 6,446 — — 6,446 — — Total 439,054 — — 439,054 — —

Inventory (Tables)

Inventory (Tables)	12 Months Ended
	Dec. 31, 2019
Inventory Disclosure [Abstract]
Schedule of Inventory, Current	The following is the inventory activity for the year ended December 31, 2019: Inventory as of December 31, 2018 $ 22,694 Purchases and capitalized improvements to inventory 274,758 Relief of inventory to cost of revenue (222,909 ) Lower of cost or net realizable value write-downs, net 47 Inventory as of December 31, 2019 $ 74,590 A summary of inventory as of December 31, 2019 and 2018 is as follows: December 31, 2019 2018 Homes for sale $ 36,982 $ 12,649 Homes not available for sale 3,163 2,328 Homes under improvement 34,445 7,717 Inventory $ 74,590 $ 22,694

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Property and Equipment	A summary of property and equipment as of December 31, 2019 and 2018 is as follows: December 31, Useful Lives (years) 2019 2018 Leasehold improvements Shorter of lease term or economic life $ 28,141 $ 19,285 Website and software development costs 2-3 27,602 19,948 Computer and office equipment 3 4,846 2,956 Software 3 595 595 Furniture 7 6,965 3,933 Construction in progress 475 — Property and equipment, gross 68,624 46,717 Accumulated depreciation and amortization (29,047 ) (21,530 ) Property and equipment, net $ 39,577 $ 25,187

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Lease, Cost	The components of lease activity were as follows: Lease Cost Classification Year Ended December 31, 2019 Operating lease cost: Operating lease cost (1) Cost of revenue $ 7,970 Operating lease cost (1) Operating expenses 3,648 Total operating lease cost $ 11,618 Finance lease cost: Amortization of right-of-use assets Cost of revenue $ 20 Interest on lease liabilities Cost of revenue 3 Total finance lease cost $ 23 (1) Includes lease expense with initial terms of twelve months or less of $2,180 for the year ended December 31, 2019. Lease Term and Discount Rate December 31, 2019 Weighted average remaining operating lease term (years) 6.1 Weighted average remaining finance lease term (years) 3.8 Weighted average discount rate for operating leases 4.4 % Weighted average discount rate for finance leases 5.4 % Supplemental Cash Flow Information Year Ended Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 9,868 Operating cash flows from finance leases 3 Financing cash flows from finance leases 14 Right of use assets obtained in exchange for lease liabilities Operating leases $ 58,669 Finance leases 274
Lessee, Operating Lease, Liability, Maturity	Maturity of Lease Liabilities Operating Leases Financing Leases 2020 $ 14,776 $ 60 2021 14,252 60 2022 13,506 60 2023 12,541 46 2024 10,947 — Thereafter 16,914 — Total lease payments $ 82,936 $ 226 Less: Interest and other (1) (11,865 ) (21 ) Present value of lease liabilities $ 71,071 $ 205 (1) Interest and other consists of interest expense related to capitalized right of use operating lease liabilities of $10,132 , interest expense related to capitalized right of use financing lease liabilities of $21 , commitments related to operating leases that have not yet commenced, and operating leases with initial terms of twelve months or less.

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Payments	Future payments due under these agreements as of December 31, 2019 are as follows: Leases (1) Other Commitments 2020 $ 14,836 $ 26,048 2021 14,312 4,779 2022 13,566 5,148 2023 12,587 — 2024 and thereafter 27,861 — Total future minimum payments $ 83,162 $ 35,975 (1) The future minimum lease payments are presented on the same basis as the financial information presented in our consolidated financial statements and notes for the year ended December 31, 2018, as included in our Annual Report on Form 10-K for such period.

Acquired Intangible Assets (Tab

Acquired Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite-Lived Intangible Assets	The following table presents details of our intangible assets subject to amortization as of December 31, 2019 and 2018. December 31, 2019 December 31, 2018 Useful Gross Accumulated Net Gross Accumulated Amortization Net Trade Names 10 $ 1,040 $ (546 ) $ 494 $ 1,040 $ (442 ) $ 598 Developed technology 10 2,980 (1,564 ) 1,416 2,980 (1,266 ) 1,714 Customer relationships 10 860 (452 ) 408 860 (366 ) 494 $ 4,880 $ (2,562 ) $ 2,318 $ 4,880 $ (2,074 ) $ 2,806

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	12 Months Ended
	Dec. 31, 2019
Payables and Accruals [Abstract]
Schedule of Accrued Liabilities	The following table presents the detail of accrued liabilities as of the dates presented: December 31, 2019 2018 Accrued compensation and benefits $ 30,462 $ 22,862 Miscellaneous accrued liabilities 7,517 7,975 Total accrued liabilities $ 37,979 $ 30,837

Other Payables (Tables)

Other Payables (Tables)	12 Months Ended
	Dec. 31, 2019
Payables and Accruals [Abstract]
Schedule of Accounts Payable and Accrued Liabilities	The following table presents the detail of other payables as of the dates presented: December 31, 2019 2018 Customer deposits $ 7,109 $ 6,226 Miscellaneous payables 775 318 Total other payables $ 7,884 $ 6,544

Equity and Equity Compensatio_2

Equity and Equity Compensation Plans (Tables)	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Schedule of Reserved Shares of Common Stock	We have reserved shares of common stock for future issuance under our ESPP as follows: Year Ended December 31, 2019 2018 Shares available for issuance at beginning of period 2,890,973 2,414,688 Shares issued during the period 490,717 425,228 Total shares available for future issuance at end of period 2,400,256 1,989,460 We have reserved shares of common stock for future issuance under our 2017 EIP as follows: December 31, 2019 2018 Stock options issued and outstanding 7,792,181 9,435,349 Restricted stock units outstanding 5,023,412 3,264,702 Shares available for future equity grants 7,100,499 5,068,013 Total shares reserved for future issuance 19,916,092 17,768,064
Schedule of Valuation Assumptions	The weighted-average grant date fair value and the assumptions used in calculating fair values of shares forecasted to be issued pursuant to our ESPP are as follows: For the Offering Period beginning July 1, 2019 For the Offering Period beginning January 1, 2019 Expected life 0.5 years 0.5 years Volatility 39.60% 42.25% Risk-free interest rate 2.10% 2.51% Dividend yield —% —% Weighted-average grant date fair value $4.59 $3.80 December 31, 2019 2018 2017 Expected life 6.5 years — 7 years Volatility 33.76% —% 37.88%-40.97% Risk-free interest rate 2.12% —% 1.96%-2.26% Dividend yield —% —% —% Weighted-average grant date fair value $3.22 — $4.86
Schedule of Stock Option Activity	The following table summarizes activity for stock options for the year ended December 31, 2019 : Weighted- Average Exercise Price Weighted Average Remaining Contractual Life (years) Outstanding as of January 1, 2019 9,435,349 $ 6.48 6.06 $ 74,669 Options granted 150,000 27.50 — — Options exercised (1,666,162 ) 5.74 Options forfeited (116,398 ) 9.16 Options canceled (10,608 ) 8.75 Outstanding as of December 31, 2019 7,792,181 $ 7.00 5.28 $ 111,122 Options exercisable as of December 31, 2019 7,043,042 $ 6.35 5.05 $ 104,141
Schedule of Share-based Compensation, Restricted Stock Units Award Activity	The following table summarizes activity for restricted stock units for the year ended December 31, 2019: Restricted Stock Units Weighted Average Grant-Date Fair Value Outstanding as of January 1, 2019 3,264,702 $ 19.68 Granted 3,184,465 18.19 Vested (966,037 ) 19.95 Forfeited or canceled (459,718 ) 19.65 Outstanding as of December 31, 2019 5,023,412 $ 18.69
Schedule of Allocation of Share-based Compensation Costs	The following table details, for each period indicated, (i) our stock-based compensation net of forfeitures, and the amount capitalized in internally developed software and (ii) includes changes to the probability of achieving outstanding performance-based equity awards, each as included in our consolidated statements of operations: Year Ended December 31, 2019 2018 2017 Cost of revenue $ 6,087 $ 5,567 $ 2,902 Technology and development 12,362 7,576 3,325 Marketing 1,418 662 487 General and administrative 7,947 6,633 4,387 Total stock-based compensation $ 27,814 $ 20,438 $ 11,101

Net Loss per Share Attributab_2

Net Loss per Share Attributable to Common Stock (Tables)	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Earnings Per Share	The following table sets forth the calculation of basic and diluted net loss per share attributable to common stock during the periods presented: Year Ended December 31, 2019 2018 2017 Numerator: Net loss $ (80,805 ) $ (41,978 ) $ (15,002 ) Accretion of preferred stock — — (175,915 ) Net loss attributable to common stock—basic and diluted $ (80,805 ) $ (41,978 ) $ (190,917 ) Denominator: Weighted average shares —basic and diluted 91,583,533 85,669,039 42,722,114 Net loss per share attributable to common stock—basic and diluted $ (0.88 ) $ (0.49 ) $ (4.47 )
Summary of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following outstanding shares of common stock equivalents were excluded from the computation of the diluted net loss per share attributable to common stock for the periods presented because their effect would have been anti-dilutive. For the year ended December 31, 2017, shares of the redeemable convertible preferred stock were anti-dilutive. However, because the preferred stock converted into common stock on a one -for-one basis on August 2, 2017 upon the completion of our IPO, we included the preferred stock in the weighted average shares outstanding for the year ended December 31, 2017. Year Ended December 31, 2019 2018 2017 Stock options outstanding 7,792,181 9,435,349 13,180,950 Restricted stock units outstanding 5,023,412 3,264,702 981,276 Employee stock purchase plan — — — Total 12,815,593 12,700,051 14,162,226

Income Taxes Income Taxes (Tabl

Income Taxes Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Schedule of Deferred Tax Assets and Liabilities	The following table represents the significant components of our deferred tax assets and liabilities for the periods presented: December 31, 2019 2018 Deferred tax assets Net operating loss carryforwards $ 49,211 $ 31,311 Credit carryforwards 8,638 6,655 Stock-based compensation 5,142 4,073 Compensation accruals 2,297 1,873 Lease liability 18,404 — Accruals and reserves 795 3,223 Gross deferred tax assets 84,487 47,135 Valuation allowance (62,274 ) (38,010 ) Total deferred tax assets, net of valuation allowance 22,213 9,125 Deferred tax liabilities Intangible assets (605 ) (734 ) Prepaid expenses (1,688 ) (1,503 ) Convertible senior notes (5,359 ) (6,888 ) Right-of-use assets (13,579 ) — Fixed assets (982 ) — Total deferred tax liabilities (22,213 ) (9,125 ) Net deferred tax assets and liabilities $ — $ —
Summary of Operating Loss Carryforwards	The following table represents our net operating loss ("NOL") carryforwards as of December 31, 2019 and 2018 : December 31, 2019 2018 Federal $ 195,133 $ 125,850 Various states 10,421 6,180 Foreign 1,212 —
Schedule of Effective Income Tax Rate Reconciliation	reconciliation of the U.S. federal income tax at statutory rate to our effective income tax rate: December 31, 2019 2018 2017 U.S. federal income tax at statutory rate 21.00 % 21.00 % 34.00 % State taxes (net of federal benefit) 4.71 5.67 2.40 Stock-based compensation 1.20 7.51 (14.74 ) Permanent differences (0.97 ) (0.57 ) (0.29 ) Federal research and development credit 2.45 4.26 7.08 Change in valuation allowance (29.73 ) (37.33 ) (27.79 ) Other 1.34 (0.54 ) (0.66 ) Change in valuation allowance for Tax Act impact — — 84.37 Change in deferred balance before valuation allowance for Tax Reform impact — — (84.37 ) Effective income tax rate — % — % — %
Schedule of Unrecognized Tax Benefits Roll Forward	The following table summarizes the activity related to unrecognized tax benefits: December 31, 2019 2018 Unrecognized benefit—beginning of year $ 1,663 $ 1,057 Gross decreases—prior year tax positions (127 ) — Gross increases—current year tax positions 623 606 Unrecognized benefit—end of year $ 2,159 $ 1,663

Debt - (Tables)

Debt - (Tables)	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	The following table summarizes borrowings under this facility as of the period presented: Lender Borrowing Capacity as of December 31, 2019 Borrowings as of December 31, 2019 Goldman Sachs Bank USA $ 100,000 $ 4,444 Lender Borrowing Capacity as of December 31, 2019 Borrowings as of Borrowings as of December 31, 2018 Western Alliance Bank $ 24,500 $ 8,489 $ 1,141 Texas Capital Bank, N.A. 24,500 10,210 3,592 Flagstar Bank, FSB 15,000 2,603 N/A Total $ 64,000 $ 21,302 $ 4,733
Convertible Senior Notes	The convertible senior notes consisted of the following: Year Ended December 31, 2019 2018 Principal $ 143,750 $ 143,750 Less: debt discount, net of amortization (21,231 ) (26,636 ) Less: debt issuance costs, net of amortization (2,803 ) (3,528 ) Net carrying amount of the convertible senior notes $ 119,716 $ 113,586
Interest Income and Interest Expense Disclosure	The following table sets forth total interest expense recognized related to the convertible senior notes for the periods presented: Year Ended December 31, 2019 2018 Amortization of debt discount $ 5,405 $ 2,280 Amortization of debt issuance costs 724 304 Total amortization of debt issuance costs and accretion of equity portion 6,129 2,584 Contractual interest expense 2,516 1,097 Total interest expense related to the convertible senior notes $ 8,645 $ 3,681

Description of Business and S_3

Description of Business and Summary of Significant Accounting Policies - Narrative (Details)	Aug. 02, 2017USD ($)$ / sharesshares	Dec. 31, 2019USD ($)investment_typeinventory_category	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Common stock issued upon conversion (in shares) | shares	55,422,002
Conversion basis	1
Number of types of investments | investment_type		2
Purchases of investments		$ 2,000,000
Number of inventory categories | inventory_category		3
Real estate rental period		30 days
Intangible assets, useful life		10 years
Goodwill		$ 9,186,000	$ 9,186,000
Goodwill, impaired, accumulated impairment loss		0
Advertising costs		62,536,000	33,457,000	$ 21,902,000
Advertising production costs		2,029,000	$ 1,644,000	$ 1,609,000
Operating lease, right-of-use asset		52,004,000
Operating lease, liability		$ 71,071,000
Vehicles
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Lessee, finance lease, term of contract		4 years
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, estimated useful lives		P2Y
Operating lease term		1 year
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, estimated useful lives		P3Y
Operating lease term		11 years
IPO
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Shares sold in offering (in shares) | shares	10,615,650
Share price (in dollars per share) | $ / shares	$ 15
Net proceeds from stock offering	$ 144,380,000
Over-Allotment Option
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Shares sold in offering (in shares) | shares	1,384,650
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, right-of-use asset		$ 33,953,000
Operating lease, liability		$ 49,395,000

Segment Reporting and Revenue -

Segment Reporting and Revenue - Narrative (Details)	12 Months Ended
	Dec. 31, 2019segment
Segment Reporting [Abstract]
Number of operating segments	5
Number of reportable segments	2

Segment Reporting and Revenue_2

Segment Reporting and Revenue - Reconciliation of Operating Profit (Loss) from Segments to Consolidated (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenue	$ 779,796	$ 486,920	$ 370,036
Cost of revenue	635,693	367,496	258,216
Gross profit	144,103	119,424	111,820
Operating expenses	223,349	163,358	127,792
Interest income	7,146	5,416	882
Interest expense	(8,928)	(3,681)	0
Other income, net	223	221	88
Net loss	(80,805)	(41,978)	(15,002)
Operating Segments | Real estate services
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenue	523,540	432,168	351,570
Cost of revenue	373,150	309,069	237,832
Gross profit	150,390	123,099	113,738
Operating Segments | Real estate services | Brokerage revenue
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenue	496,480	406,293	330,372
Operating Segments | Real estate services | Partner revenue
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenue	27,060	25,875	21,198
Operating Segments | Properties
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenue	240,507	44,993	10,491
Cost of revenue	245,189	46,613	10,384
Gross profit	(4,682)	(1,620)	107
Operating Segments | Other
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenue	17,634	9,882	7,975
Cost of revenue	19,239	11,937	10,000
Gross profit	(1,605)	(2,055)	(2,025)
Intercompany eliminations
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenue	(1,885)	(123)	0
Cost of revenue	(1,885)	(123)	0
Gross profit	$ 0	$ 0	$ 0

Segment Reporting and Revenue_3

Segment Reporting and Revenue - Summary of Accrued Revenue (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting [Abstract]
Accounts receivable	$ 19,388	$ 15,529
Less: Allowance for doubtful accounts	(165)	(166)	$ (160)	$ (150)
Accounts receivable, net	$ 19,223	$ 15,363

Segment Reporting and Revenue_4

Segment Reporting and Revenue - Activity in Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	$ 166	$ 160	$ 150
Charges	(15)	43	81
Write-offs		(37)	(71)
Write-offs	14
Balance, end of period	$ 165	$ 166	$ 160

Financial Instruments Financial

Financial Instruments Financial Instruments - Narrative (Details)	12 Months Ended
	Dec. 31, 2019USD ($)
Fair Value Disclosures [Abstract]
Other-than-temporary impairment loss, debt securities, available-for-sale	$ 0

Financial Instruments - Schedul

Financial Instruments - Schedule of Assets, Liabilities, and Equity Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Assets
U.S. treasury securities	$ 70,029
U.S. treasury securities	30,978
Fair Value, Measurements, Recurring
Assets
Loans held for sale	21,985	$ 4,913
Derivative asset	500	254
Total assets	344,934	430,943
Liabilities
Total liabilities	115	141
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Loans held for sale	0	0
Derivative asset	0	0
Total assets	322,449	425,776
Liabilities
Total liabilities	0	0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Assets
Loans held for sale	21,985	4,913
Derivative asset	4	0
Total assets	21,989	4,913
Liabilities
Total liabilities	57	141
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Assets
Loans held for sale	0	0
Derivative asset	496	254
Total assets	496	254
Liabilities
Total liabilities	58	0
U.S. treasury securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
U.S. treasury securities	70,029
U.S. treasury securities	30,978
U.S. treasury securities | Fair Value, Measurements, Recurring
Assets
U.S. treasury securities	70,029
U.S. treasury securities	30,978
U.S. treasury securities | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
U.S. treasury securities	70,029
U.S. treasury securities	30,978
U.S. treasury securities | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Assets
U.S. treasury securities	0
U.S. treasury securities	0
U.S. treasury securities | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Assets
U.S. treasury securities	0
U.S. treasury securities	0
Forward sales commitments | Fair Value, Measurements, Recurring
Assets
Derivative asset	4
Liabilities
Derivative liability	57	141
Forward sales commitments | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Derivative asset	0
Liabilities
Derivative liability	0	0
Forward sales commitments | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Assets
Derivative asset	4
Liabilities
Derivative liability	57	141
Forward sales commitments | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Assets
Derivative asset	0
Liabilities
Derivative liability	0	0
Interest rate lock commitments | Fair Value, Measurements, Recurring
Assets
Derivative asset	496	254
Liabilities
Derivative liability	58
Interest rate lock commitments | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Derivative asset	0	0
Liabilities
Derivative liability	0
Interest rate lock commitments | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Assets
Derivative asset	0	0
Liabilities
Derivative liability	0
Interest rate lock commitments | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Assets
Derivative asset	496	254
Liabilities
Derivative liability	58
Money market funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Money market funds		425,776
Money market funds | Fair Value, Measurements, Recurring
Assets
Money market funds	221,442	425,776
Money market funds | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Money market funds	221,442	425,776
Money market funds | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Assets
Money market funds	0	0
Money market funds | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Assets
Money market funds	$ 0	$ 0

Financial Instruments - Investm

Financial Instruments - Investments in Debt and Marketable Equity Securities Disclosure (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Cost or Amortized Cost
Cash and cash equivalents, at carrying value	$ 234,679	$ 432,608
Restricted cash	12,769	6,446
Cash, cash equivalents, and available-for-sale debt securities, amortized cost	348,446	439,054
Unrealized Gains (Losses)
Unrealized Gains	31
Unrealized Losses	(22)
Estimated Fair Value
Restricted cash	12,769	6,446
Cash, cash equivalents, and available-for-sale debt securities	348,455	439,054
Short-term Investments
Short-term investments	70,029
Long-term Investments
Long-term investments	30,978
Cash
Cost or Amortized Cost
Cash and cash equivalents, at carrying value	13,237	6,832
Estimated Fair Value
Cash and cash equivalents, fair value disclosure	13,237	6,832
Level 1 | U.S. treasury securities
Cost or Amortized Cost
Debt securities, available-for-sale, amortized cost	100,998
Unrealized Gains (Losses)
Unrealized Gains	31
Unrealized Losses	(22)
Estimated Fair Value
Debt securities, available-for-sale	101,007
Short-term Investments
Short-term investments	70,029
Long-term Investments
Long-term investments	30,978
Level 1 | Money markets funds
Cost or Amortized Cost
Cash and cash equivalents, at carrying value	$ 221,442	425,776
Estimated Fair Value
Cash and cash equivalents, fair value disclosure		$ 425,776

Inventory (Details)

Inventory (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Homes for sale		$ 36,982	$ 12,649
Homes not available for sale		3,163	2,328
Homes under improvement		34,445	7,717
Inventory	$ 74,590	74,590	22,694
Inventory, Current [Roll Forward]
Inventory as of December 31, 2018	22,694
Purchases and capitalized improvements to inventory	274,758
Relief of inventory to cost of revenue	(222,909)
Lower of cost or net realizable value write-downs, net	47
Inventory as of December 31, 2019	$ 74,590
Lower of cost or net realizable value write-downs		$ 143	$ 190

Property and Equipment - Summar

Property and Equipment - Summary of Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 68,624	$ 46,717
Accumulated depreciation and amortization	(29,047)	(21,530)
Property and equipment, net	39,577	25,187
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	28,141	19,285
Website and software development costs
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 27,602	19,948
Website and software development costs | Minimum
Property, Plant and Equipment [Line Items]
Useful Lives (years)	2 years
Website and software development costs | Maximum
Property, Plant and Equipment [Line Items]
Useful Lives (years)	3 years
Computer and office equipment
Property, Plant and Equipment [Line Items]
Useful Lives (years)	3 years
Property and equipment, gross	$ 4,846	2,956
Software
Property, Plant and Equipment [Line Items]
Useful Lives (years)	3 years
Property and equipment, gross	$ 595	595
Furniture
Property, Plant and Equipment [Line Items]
Useful Lives (years)	7 years
Property and equipment, gross	$ 6,965	3,933
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 475	$ 0

Property and Equipment - Narrat

Property and Equipment - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Depreciation and amortization	$ 8,742	$ 7,977	$ 6,688
Capitalized computer software, gross	$ 8,396	$ 5,796	$ 4,887

Leases - Summary of Lease Cost

Leases - Summary of Lease Cost (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Operating Leased Assets [Line Items]
Operating lease cost	$ 11,618
Finance lease, right-of-use asset, amortization	20
Finance lease cost	23
Short-term lease cost	2,180
Cost of revenue
Operating Leased Assets [Line Items]
Operating lease cost	7,970
Finance lease, interest expense	3
Operating expenses
Operating Leased Assets [Line Items]
Operating lease cost	$ 3,648

Leases - Maturity of Lease Liab

Leases - Maturity of Lease Liabilities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Operating Leases
2020	$ 14,776
2021	14,252
2022	13,506
2023	12,541
2024	10,947
Thereafter	16,914
Total future minimum payments	82,936
Less: Interest and other	(11,865)
Present value of lease liabilities	71,071
Financing Leases
2020	60
2021	60
2022	60
2023	46
2024	0
Thereafter	0
Total lease payments	226
Less: Interest and other	(21)
Present value of lease liabilities	205
Operating lease capitalized interest expense	10,132
Financing lease, capitalized interest expense	$ 21

Leases - Lease Term and Discoun

Leases - Lease Term and Discount Rate (Details)	Dec. 31, 2019
Leases [Abstract]
Weighted average remaining operating lease term (years)	6 years 1 month 6 days
Weighted average remaining finance lease term (years)	3 years 9 months 18 days
Weighted average discount rate for finance leases	4.40%
Weighted average discount rate for finance leases	5.40%

Leases - Supplemental Cash Flow

Leases - Supplemental Cash Flow Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases	$ 9,868
Operating cash flows from finance leases	3
Financing cash flows from finance leases	14
Right of use assets obtained in exchange for lease liabilities
Operating leases	58,669
Finance leases	$ 274

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details)	Dec. 31, 2019
Minimum
Debt Instrument [Line Items]
Operating lease term	1 year
Maximum
Debt Instrument [Line Items]
Operating lease term	11 years
Vehicles
Debt Instrument [Line Items]
Lessee, finance lease, term of contract	4 years

Commitments and Contingencies_2

Commitments and Contingencies - Summary of Future Minimum Payments (Details) $ in Thousands	Dec. 31, 2019USD ($)
Leases
2020	$ 14,776
2021	14,252
2022	13,506
2023	12,541
Total future minimum payments	82,936
Other Commitments
2020	26,048
2021	4,779
2022	5,148
2023	0
2024 and thereafter	0
Total future minimum payments	35,975
Office Facility
Leases
2020	14,836
2021	14,312
2022	13,566
2023	12,587
2024 and thereafter	27,861
Total future minimum payments	$ 83,162

Acquired Intangible Assets - Sc

Acquired Intangible Assets - Schedule of Finite-Lived Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Useful Live (years)	10 years
Gross	$ 4,880	$ 4,880
Accumulated Amortization	(2,562)	(2,074)
Net	$ 2,318	2,806
Trade Names
Finite-Lived Intangible Assets [Line Items]
Useful Live (years)	10 years
Gross	$ 1,040	1,040
Accumulated Amortization	(546)	(442)
Net	$ 494	598
Developed technology
Finite-Lived Intangible Assets [Line Items]
Useful Live (years)	10 years
Gross	$ 2,980	2,980
Accumulated Amortization	(1,564)	(1,266)
Net	$ 1,416	1,714
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Useful Live (years)	10 years
Gross	$ 860	860
Accumulated Amortization	(452)	(366)
Net	$ 408	$ 494

Acquired Intangible Assets - Na

Acquired Intangible Assets - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization	$ 488	$ 488	$ 488
Total	2,318
2020	488
2021	488
2022	488
2023	488
2024	$ 366

Accrued Liabilities (Details)

Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Accrued compensation and benefits	$ 30,462	$ 22,862
Miscellaneous accrued liabilities	7,517	7,975
Total accrued liabilities	$ 37,979	$ 30,837

Other Payables (Details)

Other Payables (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Customer deposits	$ 7,109	$ 6,226
Miscellaneous payables	775	318
Total other payables	$ 7,884	$ 6,544

Equity and Equity Compensatio_3

Equity and Equity Compensation Plans - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	Jun. 01, 2019	Jul. 27, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jul. 26, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, authorized (in shares)			500,000,000	500,000,000
Common stock, par value (in dollars per share)			$ 0.001	$ 0.001
Preferred stock, authorized (in shares)			10,000,000
Preferred stock, par value (in dollars per share)			$ 0.001
Preferred stock, outstanding (in shares)			0	0
Unrecognized stock-based compensation, options			$ 3,573
Total grant date fair value, options vested			4,747	$ 7,089	$ 10,571
Total grant date fair value, options exercised			$ 20,811	$ 49,276	9,322
Options granted (in shares)			150,000	0
Options granted (in dollars per share)			$ 27.50
Stock-based compensation expense			$ 27,814	$ 20,438	11,101
Stock-based compensation capitalized			$ 1,280	$ 522	$ 268
2004 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life			10 years
Award vesting period			4 years
2017 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved (in shares)			2,400,256	1,989,460
2017 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved (in shares)			19,916,092	17,768,064		7,898,159
Percentage of common stock, outstanding			5.00%
Expected life			10 years
Award vesting period			4 years
Restricted stock units outstanding (in shares)			5,023,412	3,264,702
Employee Stock | 2004 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved (in shares)			0
Employee Stock | 2017 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved (in shares)		1,600,000
Percentage of common stock, outstanding		1.00%
Purchase price of common stock, percentage of market price of common stock			85.00%
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense, period for recognition			1 year 1 month 17 days
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense, period for recognition			3 years 21 days
Unrecognized stock-based compensation, other than options			$ 86,549
Restricted stock units outstanding (in shares)			5,023,412	3,264,702
Performance Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units outstanding (in shares)			314,999
Award requisite service period, achievement percentage			100.00%
Stock-based compensation expense			$ 284
Minimum | Performance Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage			0.00%
Maximum | Performance Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage			200.00%
Chief Executive Officer | Performance Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted (in shares)	150,000
Options granted (in dollars per share)	$ 27.50
Chief Executive Officer | Maximum | Performance Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted (in shares)	300,000
2018 Awards | Performance Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense			$ 610
January To December 2019 Awards | Performance Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense			$ 894

Equity and Equity Compensatio_4

Equity and Equity Compensation Plans - Summary of Common Stock Reserve for Future Issuance (in shares) (Details) - shares	Dec. 31, 2019	Dec. 31, 2018	Jul. 26, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options issued and outstanding (in shares)	7,792,181	9,435,349
2017 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options issued and outstanding (in shares)	7,792,181	9,435,349
Restricted stock units outstanding (in shares)	5,023,412	3,264,702
Shares available for future equity grants (in shares)	7,100,499	5,068,013
Total common stock reserved for future issuance (in shares)	19,916,092	17,768,064	7,898,159
2017 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total common stock reserved for future issuance (in shares)	2,400,256	1,989,460
Shares issued during the period	490,717	425,228
Shares available for issuance at beginning of period	2,890,973	2,414,688

Equity and Equity Compensatio_5

Equity and Equity Compensation Plans - Summary of Value Assumptions (Details) - $ / shares	Jul. 01, 2019	Jan. 01, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life				0 years
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life			6 years 6 months		7 years
Volatility			33.76%	0.00%
Risk-free interest rate			2.12%	0.00%
Dividend yield			0.00%	0.00%	0.00%
Weighted-average grant date fair value (in dollars per share)			$ 3.22	$ 0	$ 4.86
Minimum | Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility					37.88%
Risk-free interest rate					1.96%
Maximum | Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility					40.97%
Risk-free interest rate					2.26%
2017 Employee Stock Purchase Plan | Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life	15 days	15 days
Volatility	39.60%	42.25%
Risk-free interest rate	2.10%	2.51%
Dividend yield	0.00%	0.00%
Weighted-average grant date fair value (in dollars per share)	$ 4.59	$ 3.80

Equity and Equity Compensatio_6

Equity and Equity Compensation Plans - Schedule of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Number Of Options
Beginning balance (in shares)	9,435,349
Options granted (in shares)	150,000	0
Options exercised (in shares)	(1,666,162)
Options forfeited (in shares)	(116,398)
Options canceled (in shares)	(10,608)
Ending balance (in shares)	7,792,181	9,435,349
Options exercisable at December 31, 2018 (in shares)	7,043,042
Weighted- Average Exercise Price
Beginning balance (in dollars per share)	$ 6.48
Options granted (in dollars per share)	27.50
Options exercised (in dollars per share)	5.74
Options forfeited (in dollars per share)	9.16
Options, canceled (in dollars per share)	8.75
Ending balance (in dollars per share)	7	$ 6.48
Options exercisable at December 31, 2018 (in dollars per share)	$ 6.35
Stock Option Activity, Additional Disclosures
Weighted average remaining contractual life outstanding	5 years 3 months 10 days	6 years 21 days
Weighted average remaining contractual life exercisable	5 years 18 days
Options outstanding, Aggregate intrinsic value	$ 111,122	$ 74,669
Options exercisable, Aggregate intrinsic value	$ 104,141

Equity and Equity Compensatio_7

Equity and Equity Compensation Plans - Summary of Restricted Stock Unit Activity (Details) - Restricted Stock Units	12 Months Ended
	Dec. 31, 2019$ / sharesshares
Restricted Stock Units
Unvested outstanding at January 1, 2019 (in shares) | shares	3,264,702
Granted (in shares) | shares	3,184,465
Vested (in shares) | shares	(966,037)
Forfeited or canceled (in shares) | shares	(459,718)
Unvested outstanding at December 31, 2019 (in shares) | shares	5,023,412
Weighted Average Grant-Date Fair Value
Unvested outstanding at January 1, 2019 (in dollars per share) | $ / shares	$ 19.68
Granted (in dollars per share) | $ / shares	18.19
Vested (in dollars per share) | $ / shares	19.95
Forfeited or canceled (in dollars per share) | $ / shares	19.65
Unvested outstanding at December 31, 2019 (in dollars per share) | $ / shares	$ 18.69

Equity and Equity Compensatio_8

Equity and Equity Compensation Plans - Allocation of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	$ 27,814	$ 20,438	$ 11,101
Cost of revenue
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	6,087	5,567	2,902
Technology and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	12,362	7,576	3,325
Marketing
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	1,418	662	487
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	$ 7,947	$ 6,633	$ 4,387

Net Loss per Share Attributab_3

Net Loss per Share Attributable to Common Stock - Narrative (Details)	12 Months Ended
	Dec. 31, 2019USD ($)class	Aug. 02, 2017
Earnings Per Share [Abstract]
Number of classes of stock | class	1
Conversion basis		1
Dilutive securities, effect on basic earnings per share, dilutive convertible securities | $	$ 0

Net Loss per Share Attributab_4

Net Loss per Share Attributable to Common Stock - Computation of Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator:
Net loss	$ (80,805)	$ (41,978)	$ (15,002)
Accretion of redeemable convertible preferred stock	0	0	(175,915)
Net loss attributable to common stock—basic	(80,805)	(41,978)	(190,917)
Net loss attributable to common stock—diluted	$ (80,805)	$ (41,978)	$ (190,917)
Denominator:
Weighted average shares —basic and diluted (in shares)	91,583,533	85,669,039	42,722,114
Net loss per share attributable to common stock—basic and diluted (in dollars per share)	$ (0.88)	$ (0.49)	$ (4.47)

Net Loss per Share Attributab_5

Net Loss per Share Attributable to Common Stock - Summary of Anti-dilutive Stock Equivalents (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from earnings per share (in shares)	12,815,593	12,700,051	14,162,226
Options outstanding
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from earnings per share (in shares)	7,792,181	9,435,349	13,180,950
Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from earnings per share (in shares)	5,023,412	3,264,702	981,276
2017 Employee Stock Purchase Plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from earnings per share (in shares)	0	0	0

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Loss Carryforwards [Line Items]
Valuation allowance increase (decrease)	$ 24,264,000	$ 8,192,000	$ (8,489,000)
NOL carryforward, decrease			1,506,000
Net loss	(80,805,000)	(41,978,000)	(15,002,000)
Unrecognized tax benefits that would impact effective tax rate	0	0
Unrecognized tax benefits	2,159,000	1,663,000	1,057,000
Unrecognized tax benefits, income tax penalties and interest accrued	0	0
Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Tax credit carryforward	8,638,000	6,655,000
Research and development credits, decrease			$ 32,000
Federal
Operating Loss Carryforwards [Line Items]
Operating loss carryforward	195,133,000	$ 125,850,000
Increase (decrease) in operating loss carryforwards	$ 109,484,000

Income Taxes - Summary of Defer

Income Taxes - Summary of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets
Net operating loss carryforwards	$ 49,211	$ 31,311
Credit carryforwards	8,638	6,655
Stock-based compensation	5,142	4,073
Compensation accruals	2,297	1,873
Lease liability	18,404
Accruals and reserves	795	3,223
Gross deferred tax assets	84,487	47,135
Valuation allowance	(62,274)	(38,010)
Total deferred tax assets, net of valuation allowance	22,213	9,125
Deferred tax liabilities
Intangible assets	(605)	(734)
Prepaid expenses	(1,688)	(1,503)
Convertible senior notes	(5,359)	(6,888)
Right-of-use assets	(13,579)
Fixed assets	(982)	0
Total deferred tax liabilities	(22,213)	(9,125)
Net deferred tax assets and liabilities	$ 0	$ 0

Income Taxes - Summary of Opera

Income Taxes - Summary of Operating Loss Carryforwards (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Federal
Operating Loss Carryforwards [Line Items]
Operating loss carryforward	$ 195,133	$ 125,850
Various states
Operating Loss Carryforwards [Line Items]
Operating loss carryforward	10,421	6,180
Foreign
Operating Loss Carryforwards [Line Items]
Operating loss carryforward	$ 1,212	$ 0

Income Taxes - Effective Income

Income Taxes - Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
U.S. federal income tax at statutory rate	21.00%	21.00%	34.00%
State taxes (net of federal benefit)	4.71%	5.67%	2.40%
Stock-based compensation	1.20%	7.51%	(14.74%)
Permanent differences	(0.97%)	(0.57%)	(0.29%)
Federal research and development credit	(2.45%)	(4.26%)	(7.08%)
Change in valuation allowance	(29.73%)	(37.33%)	(27.79%)
Other nondeductible expenses and others	1.34%	(0.54%)	(0.66%)
Change in valuation allowance for Tax Act impact	0	0	0.8437
Change in deferred balance before valuation allowance for Tax Reform impact	0.00%	0.00%	(84.37%)
Effective income tax rate	0.00%	0.00%	0.00%

Income Taxes - Summary of Unrec

Income Taxes - Summary of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns
Unrecognized benefit—beginning of year	$ 1,663	$ 1,057
Gross decreases—prior year tax positions	(127)	0
Gross increases—current year tax positions	623	606
Unrecognized benefit—end of year	$ 2,159	$ 1,663

Debt - Narrative (Details)

Debt - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Jul. 23, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Inventory	$ 74,590,000	$ 22,694,000
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	247,448,000	439,055,000		$ 212,658,000	$ 67,845,000
1.75% Convertible Senior Notes due 2023
Debt Instrument [Line Items]
Stated interest rate			1.75%
Amortization of debt issuance costs	(724,000)	(304,000)
Interest expense, debt	2,516,000	1,097,000
Debt instrument, face amount			$ 143,750,000
Debt instrument, interest rate, effective percentage			7.25%
Fair Value, Inputs, Level 2 | 1.75% Convertible Senior Notes due 2023
Debt Instrument [Line Items]
Debt instrument, fair value	142,672,000	$ 117,875,000
Revolving Credit Facility
Debt Instrument [Line Items]
Net Assets	16,200,000
Inventory	7,456,000
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 5,663,000
Debt, weighted average interest rate	4.45%
Amortization of debt issuance costs	$ (256,000)
Interest expense, debt	$ 17,000
Goldman Sachs Bank USA | Revolving Credit Facility
Debt Instrument [Line Items]
Debt instrument, term	6 months
Western Alliance Bank | Warehouse Agreement Borrowings | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	2.00%
Stated interest rate	3.50%
Debt, weighted average interest rate	3.79%	5.26%
Texas Capital Bank, N.A. | Warehouse Agreement Borrowings
Debt Instrument [Line Items]
Debt instrument, decrease in rate of interest accruing on outstanding principal	0.50%
Stated interest rate	3.50%
Debt, weighted average interest rate	3.51%	4.11%
Minimum | Goldman Sachs Bank USA | Revolving Credit Facility
Debt Instrument [Line Items]
Debt instrument, floor rate of basis spread on variable rate	0.50%
Maximum | Goldman Sachs Bank USA | Revolving Credit Facility
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	2.65%
Line of Credit | Revolving Credit Facility | Flagstar Warehouse Credit Facility [Member]
Debt Instrument [Line Items]
Stated interest rate	3.00%
Debt, weighted average interest rate	3.69%
Debt instrument, termination notice period	30 days
Line of Credit | Revolving Credit Facility | London Interbank Offered Rate (LIBOR) | Flagstar Warehouse Credit Facility [Member]
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	2.00%

Debt - Warehouse Lines of Credi

Debt - Warehouse Lines of Credit (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Warehouse agreement borrowings	$ 21,302,000	$ 4,733,000
Warehouse Agreement Borrowings
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	64,000,000
Warehouse agreement borrowings	21,302,000	4,733,000
Western Alliance Bank | Warehouse Agreement Borrowings
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	24,500,000
Warehouse agreement borrowings	8,489,000	1,141,000
Texas Capital Bank, N.A. | Warehouse Agreement Borrowings
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	24,500,000
Warehouse agreement borrowings	10,210,000	$ 3,592,000
Flagstar Bank, FSB | Warehouse Agreement Borrowings
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	15,000,000
Warehouse agreement borrowings	$ 2,603,000

Debt - Secured Revolving Credit

Debt - Secured Revolving Credit Facility (Details) - Goldman Sachs Bank USA - Revolving Credit Facility	Dec. 31, 2019USD ($)
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 100,000,000
Long-term line of credit	$ 4,444,000

Debt - Convertible Senior Notes

Debt - Convertible Senior Notes (Details) - 1.75% Convertible Senior Notes due 2023 - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Principal	$ 143,750	$ 143,750
Less: debt discount, net of amortization	(21,231)	(26,636)
Less: debt issuance costs, net of amortization	(2,803)	(3,528)
Net carrying amount of the convertible senior notes	$ 119,716	$ 113,586

Debt - Schedule of Interest Exp

Debt - Schedule of Interest Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Total amortization of debt issuance costs and accretion of equity portion	$ 6,385	$ 2,584	$ 0
Total interest expense related to the convertible senior notes	8,928	3,681	$ 0
1.75% Convertible Senior Notes due 2023
Debt Instrument [Line Items]
Amortization of debt discount	5,405	2,280
Amortization of debt issuance costs	724	304
Total amortization of debt issuance costs and accretion of equity portion	6,129	2,584
Contractual interest expense	2,516	1,097
Total interest expense related to the convertible senior notes	$ 8,645	$ 3,681

Uncategorized Items - redfin10-

Label	Element	Value
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 0
Additional Paid-in Capital [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	522,000
Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ (522,000)